# NCERT Class 12-Mathematics: Chapter –5 Continuity and Differentiability Part 28

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**Question 82:**

Find .

**Answer:**

We have,

Putting

Taking log on both sides, we get

Differentiating we get

Now,

Differentiating , we get

Now,

On substituting the values of from (i) and (ii), we get

## Objective Type Questions

### Choose the Correct Answers from the Given Four Options in Each of the Exercises 83 to 96

**Question 83:**

If and . then which of the following can be a discontinuous function

(A)

(B)

(C)

(D)

**Answer: (D)**

**Question 84:**

The function is

(A) Discontinuous at only one point

(B) Discontinuous at exactly two points

(C) Discontinuous at exactly three points

(D) None of these

**Answer: (C)**

**Question 85:**

The of points where the function given by is differentiable is

(A)

(B)

(C)

(D) None of these

**Answer: (B)**

**Question 86:**

The function is discontinuous on the set

(A)

(B)

(C)

(D)

**Answer: (A)**

**Question 87:**

The function is

(A) Continuous everywhere but not differentiable at

(B) Continuous and differentiable everywhere

(C) Not continuous at

(D) None of these.

**Answer: (A)**