English

Discuss the Continuity of the Following Functions at the Indicated Point(S): F ( X ) = { 1 − X N 1 − X , X ≠ 1 N − 1 , X = 1 N ∈ N a T X = 1 - Mathematics

Advertisements
Advertisements

Question

Discuss the continuity of the following functions at the indicated point(s): 

\[f\left( x \right) = \left\{ \begin{array}{l}\frac{1 - x^n}{1 - x}, & x \neq 1 \\ n - 1 , & x = 1\end{array}n \in N \right.at x = 1\]
Advertisements

Solution

 Given:

\[f\left( x \right) = \binom{\frac{1 - x^n}{1 - x}, x \neq 1}{n - 1, x = 1}\]

Here, 

\[f\left( 1 \right) = n - 1\]

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

\[ \Rightarrow \lim_{x \to 1} f\left( x \right) = \lim_{x \to 1} \left[ \left( 1 - x \right)^{n - 1} + \ prescript{n}{}{C}_1 \left( 1 - x \right)^{n - 2} x + \ prescript{n}{}{C}_2 \left( 1 - x \right)^{n - 3} x^2 + . . . + \ prescript{n}{}{C}_{n - 1} \left( 1 - x \right)^0 x^{n - 1} \right]\]

\[\Rightarrow \lim_{x \to 1} f\left( x \right) = 0 + 0 . . . + \left( 1 \right)^{n - 1} = 1 \neq f\left( 1 \right)\]

Thus, 

\[f\left( x \right) \text{is discontinuous at} x = 1\]
shaalaa.com
  Is there an error in this question or solution?
Chapter 9: Continuity - Exercise 9.1 [Page 17]

APPEARS IN

RD Sharma Mathematics [English] Class 12
Chapter 9 Continuity
Exercise 9.1 | Q 10.5 | Page 17

RELATED QUESTIONS

Find the value of 'k' if the function

`f(X)=(tan7x)/(2x) ,  "for " x != 0 `

`=k`,            for x=0

is continuos at x=0


Examine the continuity of the following function :

`{:(,,f(x)= x^2 -x+9,"for",x≤3),(,,=4x+3,"for",x>3):}}"at "x=3`


If f(x)= `{((sin(a+1)x+2sinx)/x,x<0),(2,x=0),((sqrt(1+bx)-1)/x,x>0):}`

is continuous at x = 0, then find the values of a and b.


Examine the following function for continuity:

f(x) = `1/(x - 5)`, x ≠ 5


A function f(x) is defined as,

\[f\left( x \right) = \begin{cases}\frac{x^2 - x - 6}{x - 3}; if & x \neq 3 \\ 5 ; if & x = 3\end{cases}\]  Show that f(x) is continuous that x = 3.

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`


Discuss the continuity of the following functions at the indicated point(s): 

\[f\left( x \right) = \begin{cases}\frac{\left| x^2 - 1 \right|}{x - 1}, for & x \neq 1 \\ 2 , for & x = 1\end{cases}at x = 1\]

Discuss the continuity of the function f(x) at the point x = 0, where  \[f\left( x \right) = \begin{cases}x, x > 0 \\ 1, x = 0 \\ - x, x < 0\end{cases}\]

 


Discuss the continuity of the function f(x) at the point x = 1/2, where \[f\left( x \right) = \begin{cases}x, 0 \leq x < \frac{1}{2} \\ \frac{1}{2}, x = \frac{1}{2} \\ 1 - x, \frac{1}{2} < x \leq 1\end{cases}\] 


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

\[f\left( x \right) = \begin{cases}k( x^2 - 2x), \text{ if }  & x < 0 \\ \cos x, \text{ if }  & x \geq 0\end{cases}\] at x = 0

Determine if \[f\left( x \right) = \begin{cases}x^2 \sin\frac{1}{x} , & x \neq 0 \\ 0 , & x = 0\end{cases}\] is a continuous function?

 


Given the function  
\[f\left( x \right) = \frac{1}{x + 2}\] . Find the points of discontinuity of the function f(f(x)).

Write the value of b for which \[f\left( x \right) = \begin{cases}5x - 4 & 0 < x \leq 1 \\ 4 x^2 + 3bx & 1 < x < 2\end{cases}\]  is continuous at x = 1.

 


If f (x) = | x − a | ϕ (x), where ϕ (x) is continuous function, then


If \[f\left( x \right) = \left| \log_{10} x \right|\] then at x = 1


\[f\left( x \right) = \begin{cases}\frac{\sqrt{1 + px} - \sqrt{1 - px}}{x}, & - 1 \leq x < 0 \\ \frac{2x + 1}{x - 2} , & 0 \leq x \leq 1\end{cases}\]is continuous in the interval [−1, 1], then p is equal to

 


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


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


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


Give an example of a function which is continuos but not differentiable at at a point.


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


Write the points of non-differentiability of 

\[f \left( x \right) = \left| \log \left| x \right| \right| .\]

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


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


Find whether the following function is differentiable at x = 1 and x = 2 or not : \[f\left( x \right) = \begin{cases}x, & & x < 1 \\ 2 - x, & & 1 \leq x \leq 2 \\ - 2 + 3x - x^2 , & & x > 2\end{cases}\] .


If the function f is continuous at x = 0

Where f(x) = 2`sqrt(x^3 + 1)` + a,  for x < 0,
= `x^3 + a + b,  for x > 0
and f (1) = 2, then find a and b.


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.


Find the value of 'k' if the function 
f(x) = `(tan 7x)/(2x)`,                   for x ≠ 0.
      = k                                        for x = 0.
is continuous at x = 0.


 If the function f (x) = `(15^x - 3^x - 5^x + 1)/(x tanx)`,  x ≠ 0 is continuous at x = 0 , then find f(0).


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


Discuss the continuity of the function `f(x) = (3 - sqrt(2x + 7))/(x - 1)` for x ≠ 1

= `-1/3`   for x = 1, at x = 1


If the function f is continuous at x = 2, then find 'k' where

f(x) = `(x^2 + 5)/(x - 1),` for  1< x ≤ 2 
      = kx + 1 , for x > 2


If Y = tan-1 `[(cos 2x - sin 2x)/(sin2x + cos 2x)]` then find `(dy)/(dx)`


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 f(x) = |x| + |x – 1| is ______.


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


A continuous function can have some points where limit does not exist.


Examine the continuity of the function f(x) = x3 + 2x2 – 1 at x = 1


`lim_("x" -> "x" //4) ("cos x - sin x")/("x"- "x" /4)`  is equal to ____________.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×