# Important Questions for Class 11 Maths Chapter 13 - Limits and Derivatives

Get the important questions for class 11 Maths Chapter 13 – Limits and Derivatives here. The important questions are given here for preparing the annual examination. Go through the problems and clear your doubts while solving the problems. Students can get an idea about the type of questions asked for the examination. Here, the questions are based on the NCERT textbook and as per the syllabus of the CBSE board. The problems include all types of questions such as 1 mark, 2 marks, 4 marks, 6 marks. Also, it includes HOTS and Value-based Questions. Practice the problems provided here to achieve good marks in class 11 Maths final examination. Also, get all the chapters important questions for Maths here.

Class 11 Maths Chapter 13 – Limits and Derivatives incorporates the following important concepts such as:

• Limits
• Derivatives
• Limits of the trigonometric functions
• Algebra of the derivative of the function

Also, Check:

## Class 11 Chapter 13 – Limits and Derivatives Important Questions with Solutions

Practice the following important questions in class 11 Maths Limits and Derivatives, that should help you to solve the problems faster with accuracy.

Question 1:

Find the derivative of the function x2cosx

Solution:

Given function is x2cosx

Let y = x2cosx

Differentiate with respect to x on both sides.

Then, we get:

dy/dx = (d/dx)x2cosx

Now, using the formula, we can write the above form as:

dy/dx = x2 (d/dx) cos x + cosx (d/dx)x2

Now, differentiate the function:

dy/dx = x2 (-sinx) + cosx(2x)

Now, rearrange the terms, we will get:

dy/dx = 2x cosx – x2sinx

Question 2:

Find the positive integer “n” so that limx → 3[(xn– 3n)/(x-3)] = 108

Solution:

Given limit: limx → 3[(xn– 3n)/(x-3)] = 108

Now, we have:

limx → 3[(xn– 3n)/(x-3)] = n(3)n-1

n(3)n-1 = 108

Now, this can be written as:

4 (27) = 4(3)4-1

Therefore, by comparing the above equation, we can get:

n = 4

Therefore, the value of positive integer “n” is 4.

Question 3:

Find the derivative of f(x)=x3 using the first principle.

Solution:

By definition,

f’(x) = limh→ 0 [f(x+h)-f(x)]/h

Now, substitute f(x)=x3 in the above equation:

f’(x) = limh→ 0 [(x+h)3-x3]/h

f’(x) = limh→ 0 (x3+h3+3xh(x+h)-x3)/h

f’(x) = limh→ 0 (h2+3x(x+h))

Substitute h = 0, we get:

f’(x) = 3x2

Therefore, the derivative of the function f’(x) = x3 is 3x2.

Question 4:

Determine the derivative of cosx/(1+sinx)

Solution:

Given function: cosx/(1+sinx)

Let y = cosx/(1+sinx)

Now, differentiate the function with respect to “x”, we get

dy/dx = (d/dx) (cosx/(1+sinx))

Now, use the u/v formula in the above form, we get

dy/dx = [(1+sinx)(-sinx) – (cosx)(cosx)]/(1+sinx)2

dy/dx = (-sinx – sin2x-cos2x)/(1+sinx)2

Now, take (-) outside from the numerator, we get:

dy/dx = -(sinx + sin2.x + cos2x)/(1+sin x)2

We know that sin2.x + cos2x = 1

By substituting this, we can get:

dy/dx = -(1+sinx)/*1+sinx)2

Cancel out (1+sinx) from both numerator and denominator, we get:

dy/dx = -1/(1+sinx)

Therefore, the derivative of cosx/(1+sinx) is -1/(1+sinx)

Question 5:

Find that: limx→ 0 |x|/x is equal to:

(a)1 (b)-1 (c)0 (d)does not exists

Solution:

A correct answer is an option (d)

Explanation:

The limit mentioned here is x→0

It has two possibilities:

Case 1: x→0+

Now, substitute the limit in the given function:

limx→ 0+ |x|/x = x/x = 1

Case 2: x→0

Now, substitute the limit in the given function:

limx→ 0- |x|/x = -x/x = -1

Hence, the result for both cases varies, the solution is an option (D)

Question 6:

Evaluate the derivative of f(x) = sin2x using Leibnitz product rule

Solution:

Given function: f(x) = sin2x

Let y= sin2x

Now, by using Leibnitz product rule, we can write it as:

dy/dx = (d/dx) sin2x

Sin2x can be written as (sinx)(sinx)

Now, it becomes:

dy/dx = (d/dx) (sinx)(sinx)

dy/dx = (sinx)’(sinx) + (sinx)(sinx)’

dy/dx = cosx sinx + sinx cosx

dy/dx = 2sinx cosx

dy/dx= sin 2x

Therefore, the derivative of the function sin2x is sin2x.

### Practice Problems for Class 11 Maths Chapter 13 – Limits and Derivatives

Solve chapter 13 limits and derivatives important problems given below:

1. Evaluate: limx → 0 [(sin22x)/(sin24x)]
2. Differentiate the function with respect to x: (ax2 + cotx)(p+qcosx)
3. Show that the limits limx → 0 [(|x-4|)/(x-4)] does not exists
4. Evaluate the following limits: limy → 0 [(x+y)sec(x+y)-xsecx]/y
5. Differentiate 1/(ax2+bx+c) with respect to x.
6. Evaluate the derivative of 99x at x=100
7. Find the derivative of the following trigonometric functions:
1. 2tanx – 7secx
2. Sinxcosx
3. 5secx + 4cosx

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#### 1 Comment

1. Dominic ifeanyi

very useful well prepared example