English

If F ( X ) = ⎧ ⎪ ⎨ ⎪ ⎩ X 2 + B , 0 ≤ X < 1 4 , X = 1 X + 3 , 1 < X ≤ 2 , Then the Value of (A, B) for Which F (X) Cannot Be Continuous at X = 1, is (A) (2, 2) (B) (3, 1) (C) (4, 0) (D) (5, 2) - Mathematics

Advertisements
Advertisements

Question

If  \[f\left( x \right) = \left\{ \begin{array}a x^2 + b , & 0 \leq x < 1 \\ 4 , & x = 1 \\ x + 3 , & 1 < x \leq 2\end{array}, \right.\] then the value of (ab) for which f (x) cannot be continuous at x = 1, is

 

Options

  • (2, 2)

  • (3, 1)

  • (4, 0)

  • (5, 2)

MCQ
Advertisements

Solution

(5, 2) 

If f(x) is continuous at x = 1, then

\[\lim_{x \to 1^-} f\left( x \right) = f\left( 1 \right)\]

\[\Rightarrow \lim_{h \to 0} f\left( 1 - h \right) = 4 \left[ \because f\left( 1 \right) = 4 \right]\]
\[ \Rightarrow \lim_{h \to 0} a \left( 1 - h \right)^2 + b = 4 \]
\[ \Rightarrow \left( a + b \right) = 4\]

Thus, the possible values of (ab) can be  

\[\left( 2, 2 \right), \left( 3, 1 \right), \left( 4, 0 \right)\] . But
\[\left( a, b \right) \neq \left( 5, 2 \right)\].

Hence, for  

\[\left( a, b \right) = \left( 5, 2 \right)\],
\[f\left( x \right)\]  cannot be continuous at = 1.

 

shaalaa.com

Notes

Disclaimer: The question in the book has some error. The solution here is created according to the question given in the book.

  Is there an error in this question or solution?
Chapter 9: Continuity - Exercise 9.4 [Page 46]

APPEARS IN

RD Sharma Mathematics [English] Class 12
Chapter 9 Continuity
Exercise 9.4 | Q 32 | Page 46

RELATED QUESTIONS

Discuss the continuity of the function f, where f is defined by:

f(x) = `{(-2", if"  x <= -1),(2x", if" -1 < x <= 1),(2", if"  x > 1):}`


Discuss the continuity of the following function at the indicated point:

`f(x) = {{:(|x| cos (1/x)",", x ≠ 0),(0",", x = 0):} at  x = 0`


Find the value of 'a' for which the function f defined by

\[f\left( x \right) = \begin{cases}a\sin\frac{\pi}{2}(x + 1), & x \leq 0 \\ \frac{\tan x - \sin x}{x^3}, & x > 0\end{cases}\]  is continuous at x = 0.
 

 


In each of the following, find the value of the constant k so that the given function is continuous at the indicated point; 

\[f\left( x \right) = \begin{cases}kx + 1, \text{ if }  & x \leq \pi \\ \cos x, \text{ if }  & x > \pi\end{cases}\] at x = π

Discuss the continuity of the f(x) at the indicated points:  f(x) = | x − 1 | + | x + 1 | at x = −1, 1.

 

For what value of k is the following function continuous at x = 2? 

\[f\left( x \right) = \begin{cases}2x + 1 ; & \text{ if } x < 2 \\ k ; & x = 2 \\ 3x - 1 ; & x > 2\end{cases}\]

Find the points of discontinuity, if any, of the following functions:  \[f\left( x \right) = \begin{cases}\frac{\sin 3x}{x}, & \text{ if }   x \neq 0 \\ 4 , & \text{ if }  x = 0\end{cases}\]

 


In the following, determine the value of constant involved in the definition so that the given function is continuou:  \[f\left( x \right) = \begin{cases}5 , & \text{ if }  & x \leq 2 \\ ax + b, & \text{ if } & 2 < x < 10 \\ 21 , & \text{ if }  & x \geq 10\end{cases}\]


Define continuity of a function at a point.

 

Find f (0), so that  \[f\left( x \right) = \frac{x}{1 - \sqrt{1 - x}}\]  becomes continuous at x = 0.

 


If  \[f\left( x \right) = \frac{1}{1 - x}\] , then the set of points discontinuity of the function f (f(f(x))) is


The values of the constants ab and c for which the function  \[f\left( x \right) = \begin{cases}\left( 1 + ax \right)^{1/x} , & x < 0 \\ b , & x = 0 \\ \frac{\left( x + c \right)^{1/3} - 1}{\left( x + 1 \right)^{1/2} - 1}, & x > 0\end{cases}\] may be continuous at x = 0, are

 


Show that f(x) = |x − 2| is continuous but not differentiable at x = 2. 


Show that f(x) = x1/3 is not differentiable at x = 0.


Show that the function 

\[f\left( x \right) = \begin{cases}x^m \sin\left( \frac{1}{x} \right) &, x \neq 0 \\ 0 &, x = 0\end{cases}\]

(i) differentiable at x = 0, if m > 1
(ii) continuous but not differentiable at x = 0, if 0 < m < 1
(iii) neither continuous nor differentiable, if m ≤ 0


Discuss the continuity and differentiability of f (x) = e|x| .


Write the points where f (x) = |loge x| is not differentiable.


Let \[f\left( x \right) = \left( x + \left| x \right| \right) \left| x \right|\]


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


If \[f\left( x \right) = \left| \log_e |x| \right|\] 


If f (x) = |3 − x| + (3 + x), where (x) denotes the least integer greater than or equal to x, then f (x) is


Discuss continuity of f(x) =`(x^3-64)/(sqrt(x^2+9)-5)` For x ≠ 4 

= 10 for x = 4  at x = 4


If f is continuous at x = 0 then find f(0) where f(x) = `[5^x + 5^-x - 2]/x^2`, x ≠ 0


The total cost C for producing x units is Rs (x2 + 60x + 50) and the price is Rs (180 - x) per unit. For how many units the profit is maximum.


Examine the continuity off at x = 1, if

f (x) = 5x - 3 , for 0 ≤ x ≤ 1

       = x2 + 1 , for 1 ≤ x ≤ 2


Discuss the continuity of function f at x = 0.
Where f(X) = `[ [sqrt ( 4 + x ) - 2 ]/ ( 3x )]`, For x ≠ 0
                  = `1/12`,                      For x = 0


Examine the continuity of the followin function : 

  `{:(,f(x),=x^2cos(1/x),",","for "x!=0),(,,=0,",","for "x=0):}}" at "x=0`   


The probability distribution function of continuous random variable X is given by
f( x ) = `x/4`,  0 < x < 2
        = 0,       Otherwise
Find P( x ≤ 1)


Discuss the continuity of the function f(x) = sin x . cos x.


Show that the function f given by f(x) = `{{:(("e"^(1/x) - 1)/("e"^(1/x) + 1)",", "if"  x ≠ 0),(0",",  "if"  x = 0):}` is discontinuous at x = 0.


The function given by f (x) = tanx is discontinuous on the set ______.


For continuity, at x = a, each of `lim_(x -> "a"^+) "f"(x)` and `lim_(x -> "a"^-) "f"(x)` is equal to f(a).


y = |x – 1| is a continuous function.


f(x) = `{{:((sqrt(1 + "k"x) - sqrt(1 - "k"x))/x",",  "if" -1 ≤ x < 0),((2x + 1)/(x - 1)",",  "if"  0 ≤ x ≤ 1):}` at x = 0


Prove that the function f defined by 
f(x) = `{{:(x/(|x| + 2x^2)",",  x ≠ 0),("k",  x = 0):}`
remains discontinuous at x = 0, regardless the choice of k.


Show that f(x) = |x – 5| is continuous but not differentiable at x = 5.


If f(x) = `{{:("m"x + 1",",  "if"  x ≤ pi/2),(sin x + "n"",",  "If"  x > pi/2):}`, is continuous at x = `pi/2`, then ______.


An example of a function which is continuous everywhere but fails to be differentiable exactly at two points is ______.


The composition of two continuous function is a continuous function.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×