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RD Sharma solutions for Mathematics [English] Class 12 chapter 2 - Functions [Latest edition]

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RD Sharma solutions for Mathematics [English] Class 12 chapter 2 - Functions - Shaalaa.com
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Solutions for Chapter 2: Functions

Below listed, you can find solutions for Chapter 2 of CBSE, Karnataka Board PUC RD Sharma for Mathematics [English] Class 12.


Exercise 2.1Exercise 2.2Exercise 2.3Exercise 2.4Exercise 2.5Exercise 2.6
Exercise 2.1 [Pages 31 - 32]

RD Sharma solutions for Mathematics [English] Class 12 2 Functions Exercise 2.1 [Pages 31 - 32]

1.1Page 31

Give an example of a function which is one-one but not onto ?

1.2Page 31

Give an example of a function which is not one-one but onto ?

1.3Page 31

Give an example of a function which is neither one-one nor onto ?

2.1Page 31

Which of the following functions from A to B are one-one and onto?
 f1 = {(1, 3), (2, 5), (3, 7)} ; A = {1, 2, 3}, B = {3, 5, 7}

2.2Page 31

Which of the following functions from A to B are one-one and onto?

 f2 = {(2, a), (3, b), (4, c)} ; A = {2, 3, 4}, B = {abc}

2.3Page 31

 Which of the following functions from A to B are one-one and onto ?  

f3 = {(ax), (bx), (cz), (dz)} ; A = {abcd,}, B = {xyz}. 

3Page 31

Prove that the function f : N → N, defined by f(x) = x2 + x + 1, is one-one but not onto

4Page 31

Let A = {−1, 0, 1} and f = {(xx2) : x ∈ A}. Show that f : A → A is neither one-one nor onto.

5.01Page 31

Classify the following function as injection, surjection or bijection : f : N → N given by f(x) = x2

5.02Page 31

Classify the following function as injection, surjection or bijection :  f : Z → Z given by f(x) = x2

5.03Page 31

Classify the following function as injection, surjection or bijection : f : N → N given by f(x) = x3

5.04Page 31

Classify the following function as injection, surjection or bijection :  f : Z → Z given by f(x) = x3

5.05Page 31

Classify the following function as injection, surjection or bijection :

f : R → R, defined by f(x) = |x|

5.06Page 31

Classify the following function as injection, surjection or bijection :

f : Z → Z, defined by f(x) = x2 + x

5.07Page 31

Classify the following function as injection, surjection or bijection :

 f : Z → Z, defined by f(x) = x − 5 

5.08Page 31

Classify the following function as injection, surjection or bijection :

 f : R → R, defined by f(x) = sinx

5.09Page 31

Classify the following function as injection, surjection or bijection :

f : R → R, defined by f(x) = x3 + 1

5.1Page 31

Classify the following function as injection, surjection or bijection :

 f : R → R, defined by f(x) = x3 − x

5.11Page 31

Classify the following function as injection, surjection or bijection :

f : R → R, defined by f(x) = sin2x + cos2x

5.12Page 31

Classify the following function as injection, surjection or bijection :

f : Q − {3} → Q, defined by `f (x) = (2x +3)/(x-3)`

5.13Page 31

Classify the following function as injection, surjection or bijection :

f : Q → Q, defined by f(x) = x3 + 1

5.14Page 31

Classify the following function as injection, surjection or bijection :
f : R → R, defined by f(x) = 5x3 + 4

5.15Page 31

Classify the following function as injection, surjection or bijection :

f : R → R, defined by f(x) = 3 − 4x

5.16Page 31

Classify the following function as injection, surjection or bijection :

f : R → R, defined by f(x) = 1 + x2

5.17Page 31

Classify the following function as injection, surjection or bijection :

f : R → R, defined by f(x) = `x/(x^2 +1)`

6Page 31

If f : A → B is an injection, such that range of f = {a}, determine the number of elements in A.

7Page 31

Show that the function f : R − {3} → R − {2} given by f(x) = `(x-2)/(x-3)` is a bijection.

8.1Page 32

Let A = [-1, 1]. Then, discuss whether the following function from A to itself is one-one, onto or bijective : `f (x) = x/2`

8.2Page 32

Let A = [-1, 1]. Then, discuss whether the following function from A to itself is one-one, onto or bijective : g(x) = |x|  

8.3Page 32

Let A = [-1, 1]. Then, discuss whether the following functions from A to itself is one-one, onto or bijective : h(x) = x2 

9.1Page 32

Set of ordered pair of  a function? If so, examine whether the mapping is injective or surjective :{(xy) : x is a person, y is the mother of x}

9.2Page 32

Set of ordered pair of a function ? If so, examine whether the mapping is injective or surjective :{(ab) : a is a person, b is an ancestor of a

10Page 32

Let A = {1, 2, 3}. Write all one-one from A to itself.

11Page 32

If f : R → R be the function defined by f(x) = 4x3 + 7, show that f is a bijection.

12Page 32

Show that the exponential function f : R → R, given by f(x) = ex, is one-one but not onto. What happens if the co-domain is replaced by`R0^+` (set of all positive real numbers)?

13Page 32

Show that the logarithmic function  f : R0+ → R   given  by f (x)  loga x ,a> 0   is   a  bijection.

14Page 32

If A = {1, 2, 3}, show that a one-one function f : A → A must be onto.

15Page 32

If A = {1, 2, 3}, show that a onto function f : A → A must be one-one.

16Page 32

Find the number of all onto functions from the set A = {1, 2, 3, ..., n} to itself.

17Page 32

Give examples of two one-one functions f1 and f2 from R to R, such that f1 + f2 : R → R. defined by (f1 + f2) (x) = f1 (x) + f2 (x) is not one-one.

18Page 32

Give examples of two surjective functions f1 and f2 from Z to Z such that f1 + f2 is not surjective.

19Page 32

Show that if f1 and f2 are one-one maps from R to R, then the product f1 × f2 : R → R defined by (f1 × f2) (x) = f1 (x) f2 (x) need not be one - one.

20Page 32

Suppose f1 and f2 are non-zero one-one functions from R to R. Is `f_1 / f^2` necessarily one - one? Justify your answer. Here,`f_1/f_2 : R → R   is   given   by   (f_1/f_2) (x) = (f_1(x))/(f_2 (x))  for all  x in R .`

21Page 32

Given A = {2, 3, 4}, B = {2, 5, 6, 7}. Construct an example of each of the following:
(i) an injective map from A to B
(ii) a mapping from A to B which is not injective
(iii) a mapping from A to B.

22Page 32

Show that f : R→ R, given by f(x) = x — [x], is neither one-one nor onto.

23Page 32

Let f : N → N be defined by

`f(n) = { (n+ 1, if n  is  odd),( n-1 , if n  is  even):}`

Show that f is a bijection. 

                      [CBSE 2012, NCERT]

Exercise 2.2 [Page 46]

RD Sharma solutions for Mathematics [English] Class 12 2 Functions Exercise 2.2 [Page 46]

1.1Page 46

Find gof and fog when f : R → R and g : R → R is defined by f(x) = 2x + 3 and  g(x) = x2 + 5 .

1.2Page 54

Find fog and gof  if : f (x) = x2 g(x) = cos x .

1.2Page 46

Find gof and fog when f : R → R and g : R → R is defined by  f(x) = 2x + x2 and  g(x) = x3

1.3Page 46

Find gof and fog when f : R → R and g : R → R is defined by  f(x) = x2 + 8 and g(x) = 3x3 + 1 .

1.4Page 46

Find gof and fog when f : R → R and g : R → R is defined by  f(x) = x and g(x) = |x| .

1.4Page 54

 Find fog and gof  if  : f (x) = ex g(x) = loge x .

1.5Page 46

Find gof and fog when f : R → R and g : R → R is defined by  f(x) = x2 + 2x − 3 and  g(x) = 3x − 4 .

1.6Page 46

Find gof and fog when f : R → R and g : R → R is  defined by  f(x) = 8x3 and  g(x) = x1/3.

2Page 46

Let f = {(3, 1), (9, 3), (12, 4)} and g = {(1, 3), (3, 3) (4, 9) (5, 9)}. Show that gof and fog are both defined. Also, find fog and gof.

3Page 46

Let f = {(1, −1), (4, −2), (9, −3), (16, 4)} and g = {(−1, −2), (−2, −4), (−3, −6), (4, 8)}. Show that gof is defined while fog is not defined. Also, find gof.

4Page 46

Let A = {abc}, B = {u vw} and let f and g be two functions from A to B and from B to A, respectively, defined as :
f = {(av), (bu), (cw)}, g = {(ub), (va), (wc)}.
Show that f and g both are bijections and find fog and gof.

5Page 46

Find  fog (2) and gof (1) when : f : R → R ; f(x) = x2 + 8 and g : R → Rg(x) = 3x3 + 1.

6Page 46

Let R+ be the set of all non-negative real numbers. If f : R+ → R+ and g : R+ → R+ are defined as `f(x)=x^2` and `g(x)=+sqrtx` , find fog and gof. Are they equal functions ?

7Page 46

Let f : R → R and g : R → R be defined by f(x) = x2 and g(x) = x + 1. Show that fog ≠ gof.

8Page 46

Let f : R → R and g : R → R be defined by f(x) = + 1 and (x) = x − 1. Show that fog = gof = IR.

9Page 46

Verify associativity for the following three mappings : f : N → Z0 (the set of non-zero integers), g : Z0 → Q and h : Q → R given by f(x) = 2xg(x) = 1/x and h(x) = ex.

10Page 46

Consider f : N → Ng : N → N and h : N → R defined as f(x) = 2xg(y) = 3y + 4 and h(z) = sin z for all xyz ∈ N. Show that ho (gof) = (hogof.

11Page 46

Give examples of two functions f : N → N and g : N → N, such that gof is onto but f is not onto.

12Page 46

Give examples of two functions f : N → Z and g : Z → Z, such that gof is injective but gis not injective.

13Page 46

If f : A → B and g : B → C are one-one functions, show that gof is a one-one function.

14Page 46

If f : A → B and g : B → C are onto functions, show that gof is a onto function.

Exercise 2.3 [Pages 54 - 55]

RD Sharma solutions for Mathematics [English] Class 12 2 Functions Exercise 2.3 [Pages 54 - 55]

1.3Page 54

Find fog and gof  if : f (x) = |x|, g (x) = sin x .

1.4Page 54

Find fog and gof  if : f (x) = x+1, g(x) = `e^x`

.

1.5Page 54

Find fog and gof  if : f(x) = sin−1 x, g(x) = x2

1.6Page 54

Find fog and gof  if : f (x) = x+1, g (x) = sin x .

1.7Page 54

Find fog and gof  if : f(x)= x + 1, g (x) = 2x + 3 .

1.8Page 54

Find fog and gof  if : f(x) = c, c ∈ R, g(x) = sin `x^2`

1.9Page 54

Find fog and gof  if : f(x) = `x^2` + 2 , g (x) = 1 − `1/ (1-x)`.

2Page 54

Let f(x) = x2 + x + 1 and g(x) = sin x. Show that fog ≠ gof.

3Page 54

If f(x) = |x|, prove that fof = f.

4Page 54

If f(x) = 2x + 5 and g(x) = x2 + 1 be two real functions, then describe each of the following functions:
(1) fog
(2) gof
(3) fof
(4) f2
Also, show that fof ≠ f2

5Page 54

If f(x) = sin x and g(x) = 2x be two real functions, then describe gof and fog. Are these equal functions?

6Page 54

Let fgh be real functions given by f(x) = sin xg (x) = 2x and h (x) = cos x. Prove that fog = go (fh).

7Page 54

Let  f  be any real function and let g be a function given by g(x) = 2x. Prove that gof = f + f.

8Page 54

   if `f (x) = sqrt(1-x)` and g(x) = `log_e` x are two real functions, then describe functions fog and gof.

9Page 54

  ` if  f : (-π/2 , π/2)` → R and g : [−1, 1]→ R be defined as f(x) = tan x and g(x) = `sqrt(1 - x^2)` respectively, describe fog and gof.

10Page 54

if f (x) = `sqrt (x +3) and  g (x) = x ^2 + 1` be two real functions, then find fog and gof.

11Page 54

Let f be a real function given by f (x)=`sqrt (x-2)`
Find each of the following:

(i) fof
(ii) fofof
(iii) (fofof) (38)
(iv) f2

Also, show that fof ≠ `f^2` .

12Page 55

Let

f (x) =`{ (1 + x, 0≤ x ≤ 2) , (3 -x , 2 < x ≤ 3):}`

Find fof.

13Page 55

 If f, g : R → R be two functions defined as f(x) = |x| + x and g(x) = |x|- x, ∀x∈R" .Then find fog and gof. Hence find fog(–3), fog(5) and gof (–2).

Exercise 2.4 [Pages 68 - 69]

RD Sharma solutions for Mathematics [English] Class 12 2 Functions Exercise 2.4 [Pages 68 - 69]

1.1Page 68

State with reason whether the following functions have inverse :
f : {1, 2, 3, 4} → {10} with f = {(1, 10), (2, 10), (3, 10), (4, 10)}

1.2Page 68

State with reason whether the following functions have inverse :

g : {5, 6, 7, 8} → {1, 2, 3, 4} with g = {(5, 4), (6, 3), (7, 4), (8, 2)}

1.3Page 68

State with reason whether the following functions have inverse:

h : {2, 3, 4, 5} → {7, 9, 11, 13} with h = {(2, 7), (3, 9), (4, 11), (5, 13)}

2.1Page 68

Find f −1 if it exists : f : A → B, where A = {0, −1, −3, 2}; B = {−9, −3, 0, 6} and f(x) = 3 x.

2.2Page 68

Find f −1 if it exists : f : A → B, where A = {1, 3, 5, 7, 9}; B = {0, 1, 9, 25, 49, 81} and f(x) = x2

3Page 68

Consider f : {1, 2, 3} → {abc} and g : {abc} → {apple, ball, cat} defined as f (1) = af (2) = bf (3) = cg (a) = apple, g (b) = ball and g (c) =  cat. Show that fg and gof are invertible. Find f−1g−1 and gof−1and show that (gof)−1 = f 1o g−1

4Page 68

Let A = {1, 2, 3, 4}; B = {3, 5, 7, 9}; C = {7, 23, 47, 79} and f : A → Bg : B → C be defined as f(x) = 2x + 1 and g(x) = x2 − 2. Express (gof)−1 and f−1 og−1 as the sets of ordered pairs and verify that (gof)−1 = f−1 og−1.

5Page 68

Show that the function f : Q → Q, defined by f(x) = 3x + 5, is invertible. Also, find f−1

6Page 68

Consider f : R → R given by f(x) = 4x + 3. Show that f is invertible. Find the inverse of f.

7Page 68

Consider f : R → R+ → [4, ∞) given by f(x) = x2 + 4. Show that f is invertible with inverse f−1 of f given by f−1 `(x)= sqrt (x-4)` where R+ is the set of all non-negative real numbers.

8Page 68

If `f(x) = (4x + 3)/(6x - 4), x ≠ 2/3` show that fof(x) = x, for all `x ≠ 2/3`. What is the inverse of f?

9Page 68

Consider f : R+ → [−5, ∞) given by f(x) = 9x2 + 6x − 5. Show that f is invertible with `f^-1 (x) = (sqrt (x +6)-1)/3 .`

10Page 69

If f : R → R be defined by f(x) = x3 −3, then prove that f−1 exists and find a formula for f−1. Hence, find f−1(24) and f−1 (5).

11Page 69

A function f : R → R is defined as f(x) = x3 + 4. Is it a bijection or not? In case it is a bijection, find f−1 (3).

12Page 69

If f : Q → Qg : Q → Q are two functions defined by f(x) = 2 x and g(x) = x + 2, show that f and g are bijective maps. Verify that (gof)−1 = f−1 og −1.

13Page 69

Let A = R - {3} and B = R - {1}. Consider the function f : A → B defined by f(x) = `(x-2)/(x-3).`Show that f is one-one and onto and hence find f-1.

                    [CBSE 2012, 2014]

14Page 69

Consider the function f : R→  [-9 , ∞ ]given by f(x) = 5x2 + 6x - 9. Prove that f is invertible with -1 (y) = `(sqrt(54 + 5y) -3)/5`             [CBSE 2015]

15Page 69

Let f : N→N be a function defined as f(x)=`9x^2`+6x−5. Show that f : N→S, where S is the range of f, is invertible. Find the inverse of f and hence find `f^-1`(43) and` f^−1`(163).

16Page 69

Let f : R `{- 4/3} `- 43 →">→ R be a function defined as f(x) = `(4x)/(3x +4)` . Show that f : R - `{-4/3}`→ Rang (f) is one-one and onto. Hence, find f -1.

17Page 69

If f : R → (−1, 1) defined by `f (x) = (10^x- 10^-x)/(10^x + 10 ^-x)` is invertible, find f−1.

18Page 69

If f : R → (0, 2) defined by `f (x) =(e^x - e^(x))/(e^x +e^(-x))+1`is invertible , find f-1.

19Page 69

Let f : [−1, ∞) → [−1, ∞) be given by f(x) = (x + 1)2 − 1, x ≥ −1. Show that f is invertible. Also, find the set S = {x : f(x) = f−1 (x)}.

20Page 69

Let A = {x &epsis; R | −1 ≤ x ≤ 1} and let f : A → Ag : A → A be two functions defined by f(x) = x2 and g(x) = sin (π x/2). Show that g−1 exists but f−1 does not exist. Also, find g−1.

21Page 69

Let f be a function from R to R, such that f(x) = cos (x + 2). Is f invertible? Justify your answer.

22Page 69

If A = {1, 2, 3, 4} and B = {abcd}, define any four bijections from A to B. Also give their inverse functions.

23Page 69

Let A and B be two sets, each with a finite number of elements. Assume that there is an injective map from A to B and that there is an injective map from B to A. Prove that there is a bijection from A to B.

24.1Page 69

If f : A → Ag : A → A are two bijections, then prove that fog is an injection ?

24.2Page 69

If f : A → Ag : A → A are two bijections, then prove that fog is a surjection ?

Exercise 2.5 [Pages 72 - 74]

RD Sharma solutions for Mathematics [English] Class 12 2 Functions Exercise 2.5 [Pages 72 - 74]

1Page 72

Which one of the following graphs represents a function?

2Page 73

Which of the following graphs represents a one-one function?

3Page 73

If A = {1, 2, 3} and B = {ab}, write the total number of functions from A to B.

4Page 73

If A = {abc} and B = {−2, −1, 0, 1, 2}, write the total number of one-one functions from A to B.

5Page 73

Write the total number of one-one functions from set A = {1, 2, 3, 4} to set B = {abc}.

6Page 73

If f : R → R is defined by f(x) = x2, write f−1 (25)

7Page 73

If f : C → C is defined by f(x) = x2, write f−1 (−4). Here, C denotes the set of all complex numbers.

8Page 73

If f : R → R is given by f(x) = x3, write f−1 (1).

9Page 73

Let C denote the set of all complex numbers. A function f : C → C is defined by f(x) = x3. Write f−1(1).

10Page 73

Let f  be a function from C (set of all complex numbers) to itself given by f(x) = x3. Write f−1 (−1).

11Page 73
 If f : R → R be defined by f(x) = x4, write f−1 (1).
12Page 73

If f : C → C is defined by f(x) = x4, write f−1 (1).

13Page 73

If f : R → R is defined by f(x) = x2, find f−1 (−25).

14Page 73

If f : C → C is defined by f(x) = (x − 2)3, write f−1 (−1).

15Page 73

If f : R → R is defined by f(x) = 10 x − 7, then write f−1 (x).

16Page 73

Let \[f : \left( - \frac{\pi}{2}, \frac{\pi}{2} \right) \to R\]  be a function defined by f(x) = cos [x]. Write range (f).

17Page 73

If f : R → R defined by f(x) = 3x − 4 is invertible, then write f−1 (x).

18Page 73

If f : R → Rg : R → are given by f(x) = (x + 1)2 and g(x) = x2 + 1, then write the value of fog (−3).

19Page 73

Let A = {x ∈ R : −4 ≤ x ≤ 4 and x ≠ 0} and f : A → R be defined by \[f\left( x \right) = \frac{\left| x \right|}{x}\]Write the range of f.

20Page 73

Let \[f : \left[ - \frac{\pi}{2}, \frac{\pi}{2} \right] \to\] A be defined by f(x) = sin x. If f is a bijection, write set A.

21Page 73

Let f : R → R+ be defined by f(x) = axa > 0 and a ≠ 1. Write f−1 (x).

22Page 73

Let f : R − {−1} → R − {1} be given by\[f\left( x \right) = \frac{x}{x + 1} . \text{Write } f^{- 1} \left( x \right)\]

23Page 74

Let `f : R - {- 3/5}` → R be a function defined as `f  (x) = (2x)/(5x +3).` 

f-1 : Range of f → `R -{-3/5}`.

24Page 74

Let f : R → Rg : R → R be two functions defined by f(x) = x2 + x + 1 and g(x) = 1 − x2. Write fog (−2).

25Page 74

Let f : R → R be defined as  `f (x) = (2x - 3)/4.` write fo f-1 (1) .

26Page 74

Let f be an invertible real function. Write ( f-1  of ) (1) + ( f-1  of ) (2) +..... +( f-1 of ) (100 )

27Page 74

Let A = {1, 2, 3, 4} and B = {ab} be two sets. Write the total number of onto functions from A to B.

28Page 74

Write the domain of the real function

`f (x) = sqrtx - [x] .`

29Page 74

Write the domain of the real function

`f (x) = sqrt([x] - x) .`

30Page 74

Write the domain of the real function

`f (x) = 1/(sqrt([x] - x)`.

31Page 74

Write whether f : R → R, given by `f(x) = x + sqrtx^2` is one-one, many-one, onto or into.

32Page 74

If f(x) = x + 7 and g(x) = x − 7, x ∈ R, write fog (7).

33Page 74

What is the range of the function

`f (x) = ([x - 1])/(x -1) ?`

34Page 74

If f : R → R be defined by f(x) = (3 − x3)1/3, then find fof (x).

35Page 74

If f : R → R is defined by f(x) = 3x + 2, find f (f (x)).

36Page 74

Let A = {1, 2, 3}, B = {4, 5, 6, 7} and let f = {(1, 4), (2, 5), (3, 6)} be a function from A to B. State whether f is one-one or not.

37Page 74

If f : {5, 6} → {2, 3} and g : {2, 3} → {5, 6} are given by f = {(5, 2), (6, 3)} and g = {(2, 5), (3, 6)}, then find fog.    [NCERT EXEMPLAR]

38Page 74

Let f : R → R be the function defined by f(x) = 4x − 3 for all x ∈ R Then write f .   [NCERT EXEMPLAR]

39Page 74

Which one the following relations on A = {1, 2, 3} is a function?
f = {(1, 3), (2, 3), (3, 2)}, g = {(1, 2), (1, 3), (3, 1)}                                                                                                        [NCERT EXEMPLAR]

40Page 74

Write the domain of the real function f defined by f(x) = `sqrt (25 -x^2)`   [NCERT EXEMPLAR]

41Page 74

Let A = {abcd} and f : A → A be given by f = {( a,b ),( b , d ),( c , a ) , ( d , c )} write `f^-1`. [NCERT EXEMPLAR]

42Page 74

Let fg : R → R be defined by f(x) = 2x + l and g(x) = x2−2 for all x

∈ R, respectively. Then, find gof.  [NCERT EXEMPLAR]

43Page 74

If the mapping f : {1, 3, 4} → {1, 2, 5} and g : {1, 2, 5} → {1, 3}, given by f = {(1, 2), (3, 5), (4, 1)} and g = {(2, 3), (5, 1), (1, 3)}, then write fog. [NCERT EXEMPLAR]

44Page 74

If a function g = {(1, 1), (2, 3), (3, 5), (4, 7)} is described by g(x) = \[\alpha x + \beta\]  then find the values of \[\alpha\] and \[ \beta\] . [NCERT EXEMPLAR]

45Page 74

If f(x) = 4 −( x - 7)3 then write f-1 (x).

Exercise 2.6 [Pages 75 - 79]

RD Sharma solutions for Mathematics [English] Class 12 2 Functions Exercise 2.6 [Pages 75 - 79]

1Page 75

Let\[A = \left\{ x \in R : - 1 \leq x \leq 1 \right\} = \text{B and C} = \left\{ x \in R : x \geq 0 \right\} and\]\[S = \left\{ \left( x, y \right) \in A \times B : x^2 + y^2 = 1 \right\} \text{and } S_0 = \left\{ \left( x, y \right) \in A \times C : x^2 + y^2 = 1 \right\}\]

Then,


  •  S defines a function from A to B

  •  `S_0` defines a function from A to C

  • S0 defines a function from A to B

  •  S defines a function from A to C

2Page 75

\[f : R \to R \text{given by} f\left( x \right) = x + \sqrt{x^2} \text{ is }\]

 

 

  • injective

  • surjective

  • bijective

  • None of these

3Page 75

 \[f : A \to \text{B given by } 3^{ f\left( x \right)} + 2^{- x} = 4\] is a bijection, then

 

 

 

 

  • \[A = \left\{ x \in R : - 1 < x < \infty \right\}, B = \left\{ x \in R : 2 < x < 4 \right\}\]

  • \[A = \left\{ x \in R : - 3 < x < \infty \right\}, B = \left\{ x \in R : 2 < x < 4 \right\}\]

  • \[A = \left\{ x \in R : - 3 < x < \infty \right\}, B = \left\{ x \in R : 2 < x < 4 \right\}\]

  • None of these

4Page 75

The function f : R → R defined by

`f (x) = 2^x + 2^(|x|)` is 

 

  • one-one and onto

  • many-one and onto

  • one-one and into

  • many-one and into

5Page 75

Let the function

\[f : R - \left\{ - b \right\} \to R - \left\{ 1 \right\}\]

\[f\left( x \right) = \frac{x + a}{x + b}, a \neq b .\text{Then},\]

 

  •  f is one-one but not onto

  • f is onto but not one-one

  • f is both one-one and onto

  • None of these

6Page 75

The function 

f : A → B defined by 

f (x) = - x2 + 6x - 8 is a bijection if 

 

 

 

 

  • A = (- ∞ , 3] and B = ( - ∞, 1 ]

  •  A = [- 3 , ∞) and B = ( - ∞, 1 ]

  • A = (- ∞ , 3] and B = [ 1 ,∞)

  • A = [3 ,∞ ) and B = [ 1 ,∞ )

7Page 75

Let 

\[A = \left\{ x \in R : - 1 \leq x \leq 1 \right\} = B\] Then, the mapping\[f : A \to \text{B given by} f\left( x \right) = x\left| x \right|\] is 

 

  • injective but not surjective

  • surjective but not injective

  • bijective

  • none of these

8Page 75

Let

f : R → R be given by

\[f\left( x \right) = \left[ x^2 \right] + \left[ x + 1 \right] - 3\]

where [x] denotes the greatest integer less than or equal to x. Then, f(x) is
 


(d) one-one and onto

  • many-one and onto

  • many-one and into

  • one-one and into

  • one-one and onto

9Page 76

Let M be the set of all 2 × 2 matrices with entries from the set R of real numbers. Then, the function f : M→ R defined by f(A) = |A| for every A ∈ M, is

 

  • one-one and onto

  • neither one-one nor onto

  • one-one but-not onto

  • onto but not one-one

10Page 76

The function \[f : [0, \infty ) \to \text {R given by } f\left( x \right) = \frac{x}{x + 1} is\]

 

 

  • one-one and onto

  • one-one but not onto

  • onto but not one-one

  • onto but not one-one

11Page 76

The range of the function

\[f\left( x \right) =^{7 - x} P_{x - 3}\]

 

  • {1, 2, 3, 4, 5}

  • {1, 2, 3, 4, 5, 6}

  • {1, 2, 3, 4}

  • {1, 2, 3}

12Page 76

A function f  from the set of natural numbers to integers defined by

`{([n-1]/2," when  n is  odd"   is ),(-n/2,when  n  is  even ) :}`

 

 

  • neither one-one nor onto

  • one-one but not onto

  • onto but not one-one

  • one-one and onto both

13Page 76

Let f be an injective map with domain {xyz} and range {1, 2, 3}, such that exactly one of the following statements is correct and the remaining are false.

\[f\left( x \right) = 1, f\left( y \right) \neq 1, f\left( z \right) \neq 2 .\]

The value of

\[f^{- 1} \left( 1 \right)\] is 

 

  •  x

  • y

  • z

  • none of these

14Page 76

Which of the following functions form Z to itself are bijections?

 

 

 
 
  • \[f\left( x \right) = x^3\]

  • \[f\left( x \right) = x + 2\]

  • \[f\left( x \right) = 2x + 1\]

  • \[f\left( x \right) = x^2 + x\]

15Page 76

Which of the following functions from

\[A = \left\{ x : - 1 \leq x \leq 1 \right\}\]

to itself are bijections?

 

 

 

  • \[f\left( x \right) = \frac{x}{2}\]

  • \[g\left( x \right) = \sin\left( \frac{\pi x}{2} \right)\]

  • \[h\left( x \right) = |x|\]

  • \[k\left( x \right) = x^2\]

16Page 76

Let

\[A = \left\{ x : - 1 \leq x \leq 1 \right\} \text{and} f : A \to \text{A such that f}\left( x \right) = x|x|\]

 

  • a bijection

  • injective but not surjective

  • surjective but not injective

  • neither injective nor surjective

17Page 76

If the function\[f : R \to \text{A given by} f\left( x \right) = \frac{x^2}{x^2 + 1}\] is a surjection, then A =

 

 

  • R

  • [0, 1]

  • [0, 1]

  • [0, 1]

18Page 76

If a function\[f : [2, \infty )\text{ to B defined by f}\left( x \right) = x^2 - 4x + 5\] is a bijection, then B =

  • R

  • [1, ∞)

  • [4, ∞)

  • [5, ∞)

19Page 76

The function

\[f : R \to R\] defined by\[f\left( x \right) = \left( x - 1 \right) \left( x - 2 \right) \left( x - 3 \right)\]

(a) one-one but not onto
(b) onto but not one-one
(c) both one and onto
(d) neither one-one nor onto

  • one-one but not onto

  • onto but not one-one

  • both one and onto

  • neither one-one nor onto

20Page 76

The  function f : [-1/2, 1/2, 1/2] → [-π /2,π/2], defined by f (x) = `sin^-1` (3x - `4x^3`), is

 

  • bijection

  • injection but not a surjection

  • surjection but not an injection

  • neither an injection nor a surjection

21Page 76

Let

\[f : R \to R\]  be a function defined by

\[f\left( x \right) = \frac{e^{|x|} - e^{- x}}{e^x + e^{- x}} . \text{Then},\]
 
  •  f is a bijection

  • f is an injection only

  •  f is surjection on only

  • f is neither an injection nor a surjection

22Page 77

Let

\[f : R - \left\{ n \right\} \to R\]

\[f\left( x \right) = \frac{x - m}{x - n}, \text{where} \ m \neq n .\] Then,
 
  •  f is one-one onto

  •  f is one-one into

  •  f is many one onto

  • f is many one into

23Page 77

Let

\[f : R \to R\]
\[f\left( x \right) = \frac{x^2 - 8}{x^2 + 2}\]
Then,  f is

  • one-one but not onto

  • one-one and onto

  • onto but not one-one

  • neither one-one nor onto

24Page 77

\[f : R \to R\] is defined by

\[f\left( x \right) = \frac{e^{x^2} - e^{- x^2}}{e^{x^2 + e^{- x^2}}} is\]

 

  • one-one but not onto

  • many-one but onto

  • one-one and onto

  • neither one-one nor onto

25Page 77

The function

\[f : R \to R, f\left( x \right) = x^2\]
 
  • injective but not surjective

  • surjective but not injective

  • injective as well as surjective

  • neither injective nor surjective

26Page 77

A function f from the set of natural numbers to the set of integers defined by

\[f\left( n \right)\begin{cases}\frac{n - 1}{2}, & \text{when n is odd} \\ - \frac{n}{2}, & \text{when n is even}\end{cases}\]

 

  • neither one-one nor onto

  • one-one but not onto

  • onto but not one-one

  • one-one and onto

27Page 77

Which of the following functions from

\[A = \left\{ x \in R : - 1 \leq x \leq 1 \right\}\]

 

  • \[f\left( x \right) = |x|\]

  • \[f\left( x \right) = \sin\frac{\pi x}{2}\]

  • \[f\left( x \right) = \sin\frac{\pi x}{4}\]

  • None of these

28Page 77

\[f : Z \to Z\]  be given by

 ` f (x) = {(x/2, ", if  x is even" ) ,(0 , ", if  x  is  odd "):}`

Then,  f is

  • onto but not one-one

  • one-one but not onto

  • one-one and onto

  • neither one-one nor onto

29Page 77

The function \[f : R \to R\] defined by

\[f\left( x \right) = 6^x + 6^{|x|}\] is 

 

  • one-one and onto

  • many one and onto

  • one-one and into

  • many one and into

30Page 77

Let  \[f\left( x \right) = x^2 and g\left( x \right) = 2^x\] Then, the solution set of the equation

\[fog \left( x \right) = gof \left( x \right)\] is 


  • R

  • {0}

  • {0, 2}

  • none of these

31Page 77

If \[f : R \to R is given by f\left( x \right) = 3x - 5, then f^{- 1} \left( x \right)\] 

 

  • is given by  \[\frac{1}{3x - 5}\]  

  • is given by \[\frac{x + 5}{3}\]

  • does not exist because f is not one-one

  • does not exist because f is not onto

32Page 77

If \[g \left( f \left( x \right) \right) = \left| \sin x \right| \text{and} f \left( g \left( x \right) \right) = \left( \sin \sqrt{x} \right)^2 , \text{then}\]

 

  •  \[f\left( x \right) = \sin^2 x, g\left( x \right) = \sqrt{x}\]

  • \[f\left( x \right) = \sin x, g\left( x \right) = |x|\]

  • \[f\left( x \right) = x^2 , g\left( x \right) = \sin \sqrt{x}\]

  •  f and g cannot be determied

33Page 78

The inverse of the function

\[f : R \to \left\{ x \in R : x < 1 \right\}\] given by

\[f\left( x \right) = \frac{e^x - e^{- x}}{e^x + e^{- x}}\] is 

 

  • \[\frac{1}{2} \log \frac{1 + x}{1 - x}\]

  •  \[\frac{1}{2} \log \frac{2 + x}{2 - x}\]

  • \[\frac{1}{2} \log \frac{1 - x}{1 + x}\]

  • none of these

34Page 78

Let

 \[A = \left\{ x \in R : x \geq 1 \right\}\] The inverse of the function, 

\[f : A \to A\] given by

\[f\left( x \right) = 2^{x \left( x - 1 \right)} , is\]

 

  • \[\left( \frac{1}{2} \right)^{x \left( x - 1 \right)}\]

  • \[\frac{1}{2} \left\{ 1 + \sqrt{1 + 4 \log_2 x} \right\}\]

  •  \[\frac{1}{2} \left\{ 1 - \sqrt{1 + 4 \log_2 x} \right\}\]

  • not defined

35Page 78

Let

\[A = \left\{ x \in R : x \leq 1 \right\} and f : A \to A\] be defined as

\[f\left( x \right) = x \left( 2 - x \right)\] Then,

\[f^{- 1} \left( x \right)\] is

  • \[1 + \sqrt{1 - x}\]

  • \[1 - \sqrt{1 - x}\]

  • \[\sqrt{1 - x}\]

  • \[1 \pm \sqrt{1 - x}\]

36Page 78

Let  \[f\left( x \right) = \frac{1}{1 - x} . \text{Then}, \left\{ f o \left( fof \right) \right\} \left( x \right)\]

 

  • \[\text{x for all x} \in R\]

  •  \[\text{x for all x} \in R - \left\{ 1 \right\}\]

  •  \[\text{x for all x} \in R - \left\{ 0, 1 \right\}\]

  • none of these

37Page 78

If the function

\[f : R \to R\]  be such that

\[f\left( x \right) = x - \left[ x \right]\] where [x] denotes the greatest integer less than or equal to x, then \[f^{- 1} \left( x \right)\]

 

  •  \[\frac{1}{x - \left[ x \right]}\]

  • [x] − x

  • not defined

  • none of these

38Page 78

If  \[F : [1, \infty ) \to [2, \infty )\] is given by

\[f\left( x \right) = x + \frac{1}{x}, then f^{- 1} \left( x \right)\]

 

  • \[\frac{x + \sqrt{x^2 - 4}}{2}\]

  • \[\frac{x}{1 + x^2}\]

  • \[\frac{x - \sqrt{x^2 - 4}}{2}\]

  • \[1 + \sqrt{x^2 - 4}\]

39Page 78
 Let
\[g\left( x \right) = 1 + x - \left[ x \right] \text{and} f\left( x \right) = \begin{cases}- 1, & x < 0 \\ 0, & x = 0, \\ 1, & x > 0\end{cases}\] where [x] denotes the greatest integer less than or equal to x. Then for all \[x, f \left( g \left( x \right) \right)\] is equal to

  • x

  • 1

  • f(x)

  •  g(x)

40Page 78

Let  \[f\left( x \right) = \frac{\alpha x}{x + 1}, x \neq - 1\] Then, for what value of α is \[f \left( f\left( x \right) \right) = x?\]

 

  • \[\sqrt{2}\]

  • \[- \sqrt{2}\]

  • 1

  • -1

41Page 78

The distinct linear functions that map [−1, 1] onto [0, 2] are

  • \[f\left( x \right) = x + 1, g\left( x \right) = - x + 1\]

  • \[f\left( x \right) = x - 1, g\left( x \right) = x + 1\]

  • \[f\left( x \right) = - x - 1, g\left( x \right) = x - 1\]

  • None of these

42Page 78

Let

\[f : [2, \infty ) \to X\] be defined by

\[f\left( x \right) = 4x - x^2\] Then, f is invertible if X =

 

  •  \[[2, \infty )\]

  •  \[( - \infty , 2]\]

  •  \[( - \infty , 4]\]

  • \[[4, \infty )\]

43Page 78

If  \[f : R \to \left( - 1, 1 \right)\] is defined by

\[f\left( x \right) = \frac{- x|x|}{1 + x^2}, \text{ then } f^{- 1} \left( x \right)\] equals

 

  • \[\sqrt{\frac{\left| x \right|}{1 - \left| x \right|}}\]

  • \[\text{ Sgn } \left( x \right) \sqrt{\frac{\left| x \right|}{1 - \left| x \right|}}\]

  •  \[- \sqrt{\frac{x}{1 - x}}\]

  • None of these

44Page 79

Let [x] denote the greatest integer less than or equal to x. If \[f\left( x \right) = \sin^{- 1} x, g\left( x \right) = \left[ x^2 \right]\text{  and } h\left( x \right) = 2x, \frac{1}{2} \leq x \leq \frac{1}{\sqrt{2}}\]

 

  • \[\text{fogoh}\left( x \right) = \frac{\pi}{2}\]

  • fogoh (x) = π

     

  •  \[\text{ho f og = hogo f}\]

  • \[\text{ho f og ≠  hogo f}\]

     

45Page 79

If  \[g\left( x \right) = x^2 + x - 2\text{ and} \frac{1}{2} gof\left( x \right) = 2 x^2 - 5x + 2\] is equal to

  • \[2 x - 3\]

  • \[2 x + 3\]

  • \[2 x^2 + 3x + 1\]

  • 2   \[x^2 - 3x - 1\]

46Page 79

If  \[f\left( x \right) = \sin^2 x\] and the composite function   \[g\left( f\left( x \right) \right) = \left| \sin x \right|\] then g(x) is equal to

  • \[\sqrt{x - 1}\]

  • \[\sqrt{x}\]

  • \[\sqrt{x + 1}\]

  • \[- \sqrt{x}\]

47Page 79

If \[f : R \to R\] is given by \[f\left( x \right) = x^3 + 3, \text{then} f^{- 1} \left( x \right)\] is equal to

 

  •  \[x^{1/3} - 3\]

  •  \[x^{1/3} + 3\]

  • \[\left( x - 3 \right)^{1/3}\]

  • \[x + 3^{1/3}\]

48Page 79

Let \[f\left(x\right) = x^3\] be a function with domain {0, 1, 2, 3}. Then domain of \[f^{-1}\] is ______.

  • {3, 2, 1, 0}

  • {0, −1, −2, −3}

  • {0, 1, 8, 27}

  • {0, −1, −8, −27}

49Page 78

Let 
\[f : R \to R\]  be given by \[f\left( x \right) = x^2 - 3\] Then, \[f^{- 1}\] is given by 

 

  • \[\sqrt{x + 3}\]

  • \[\sqrt{x} + 3\]

  •  \[x + \sqrt{3}\]

  • None of these

50Page 79

Mark the correct alternative in the following question:

Let f : → R be given by f(x) = tanx. Then, f-1(1) is

 

 

  •  \[\frac{\pi}{4}\]   

  • \[\left\{ n\pi + \frac{\pi}{4}: n \in Z \right\}\]

  • does not exist    

  • none of these

51Page 79

Mark the correct alternative in the following question:
Let f : R→ R be defined as, f(x) =  \[\begin{cases}2x, if x > 3 \\ x^2 , if 1 < x \leq 3 \\ 3x, if x \leq 1\end{cases}\] 

Then, find f( \[-\]1) + f(2) + f(4)

 

  • 14    

  • 5       

  • none of these

52Page 79

Mark the correct alternative in the following question:
Let A = {1, 2, ... , n} and B = {a, b}. Then the number of subjections from A into B is

  •  nP2 

  • 2n - 2

  • 2n - 1

  •  nC2

53Page 79

Mark the correct alternative in the following question:

If the set A contains 5 elements and the set B contains 6 elements, then the number of one-one and onto mappings from A to B is

  • 720        

  • 120   

  • none of these

54Page 79

Mark the correct alternative in the following question:
If the set A contains 7 elements and the set B contains 10 elements, then the number one-one functions from A to B is

  • 10C7 

  • 10C7\[\times\] 7!

  • 710 

  • 107

55Page 79

Mark the correct alternative in the following question:
Let f :  \[-\] \[\left\{ \frac{3}{5} \right\}\] \[\to\]  R be defined by f(x) = \[\frac{3x + 2}{5x - 3}\] Then,

 

  • f-1 (x) = f (x)

  • `f^-1 (x) = - f(x)`

  • fo f(x) = - x 

  • `f^-1(x) = 1/19f(x)`

Solutions for 2: Functions

Exercise 2.1Exercise 2.2Exercise 2.3Exercise 2.4Exercise 2.5Exercise 2.6
RD Sharma solutions for Mathematics [English] Class 12 chapter 2 - Functions - Shaalaa.com

RD Sharma solutions for Mathematics [English] Class 12 chapter 2 - Functions

Shaalaa.com has the CBSE, Karnataka Board PUC Mathematics Mathematics [English] Class 12 CBSE, Karnataka Board PUC solutions in a manner that help students grasp basic concepts better and faster. The detailed, step-by-step solutions will help you understand the concepts better and clarify any confusion. RD Sharma solutions for Mathematics Mathematics [English] Class 12 CBSE, Karnataka Board PUC 2 (Functions) include all questions with answers and detailed explanations. This will clear students' doubts about questions and improve their application skills while preparing for board exams.

Further, we at Shaalaa.com provide such solutions so students can prepare for written exams. RD Sharma textbook solutions can be a core help for self-study and provide excellent self-help guidance for students.

Concepts covered in Mathematics [English] Class 12 chapter 2 Functions are Basics of Relations & Functions, Types of Relations, Types of Functions, Overview of Relations and Functions, Equivalence Class and Relation, Composition of Functions, Invertible Functions.

Using RD Sharma Mathematics [English] Class 12 solutions Functions exercise by students is an easy way to prepare for the exams, as they involve solutions arranged chapter-wise and also page-wise. The questions involved in RD Sharma Solutions are essential questions that can be asked in the final exam. Maximum CBSE, Karnataka Board PUC Mathematics [English] Class 12 students prefer RD Sharma Textbook Solutions to score more in exams.

Get the free view of Chapter 2, Functions Mathematics [English] Class 12 additional questions for Mathematics Mathematics [English] Class 12 CBSE, Karnataka Board PUC, and you can use Shaalaa.com to keep it handy for your exam preparation.

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