Before the exam, make sure you revise the standard limit formulas, the definition of derivative using first principles, and the basic differentiation rules. These formulas are the foundation for solving introductory Calculus problems in both board and competitive examinations.
Questions are commonly asked from standard limits, evaluation of limits, continuity, derivatives from first principles, and basic differentiation. Concept-based questions combining multiple limit properties are also frequently seen in JEE Advanced.
Students can generally expect 1–2 questions from this chapter in JEE Main. Since it serves as the foundation for Calculus, its concepts are also applied indirectly in higher-weightage chapters such as Applications of Derivatives, Continuity & Differentiability, and Differential Equations.
The most frequent mistakes include directly substituting values into indeterminate forms, forgetting standard limits, making algebraic simplification errors, and incorrectly applying the definition of derivatives. Regular practice with conceptual questions helps eliminate these errors.
Start by revising all standard limit formulas and derivative rules. Next, solve a few representative problems on limits, continuity, and first-principle differentiation. Finally, attempt Previous Years' Questions (PYQs) under timed conditions to strengthen speed, accuracy, and conceptual understanding.
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Class 11 Maths Chapter 12 Limits and Derivatives Revision Notes
The concepts of Limits and Derivatives mark the beginning of Calculus, one of the most important branches of Mathematics. Whether it is calculating the speed of a moving object, analyzing the growth of a population, optimizing engineering designs, or studying rates of change in Physics and Economics, derivatives play a crucial role. This chapter introduces the fundamental ideas of limits, the behavior of functions near a point, and the concept of the derivative as the instantaneous rate of change and slope of a tangent. These concepts form the foundation for advanced Calculus and are extensively tested in JEE Main, JEE Advanced, and CBSE Board examinations.
At ALLEN, our expert faculty have prepared these Class 11 Maths Chapter 12: Limits and Derivatives Revision Notes to help students build strong conceptual clarity in Calculus. These notes include concise theory, standard limit results, derivative formulas, shortcut techniques, solved illustrations, and previous years' question analysis. Whether you're preparing for board examinations or competitive exams, these revision notes will help you master the fundamentals of Calculus and solve problems with confidence.
1.0Chapter Snapshot
Topic
Overview
Limits
Concept and evaluation of limits
Standard Limits
Frequently used limit formulas
Left-Hand and Right-Hand Limits
Existence of limits
Continuity (Basic Idea)
Behavior of functions near a point
Derivative
Instantaneous rate of change
Geometrical Interpretation
Slope of a tangent
Algebra of Derivatives
Basic derivative rules
Applications
Foundation of Calculus and JEE problems
2.0Chapter 12 Smart Study Material by ALLEN Experts: Download PDFs
Resource
Status
Chapter Mock Test Paper
Chapter Mock Test Paper Solution
On this page
1.0Chapter Snapshot
2.0Chapter 12 Smart Study Material by ALLEN Experts: Download PDFs
Limits and Derivatives are fundamental concepts in calculus that lay the groundwork for more advanced topics. Understanding them is crucial for solving problems related to rates of change, optimization, and motion, among others.
1.0What are Limits and Derivatives in Mathematics?
Limits help us understand the behavior of functions as they approach a certain point. Formally, the limit of a function f(x) as x approaches a value a is the value that f(x) gets closer to as x gets closer to a. It’s expressed as:
limx→af(x)=L
Where L is the limit value.
Following fig. show the graphs of three functions. Note that in part(c), f(a) is not defined and part (b), f(a) ≠ L. But in each case, it happens at a. It is true that limx→af(x)=L.
Derivatives, on the other hand, measure how a function changes as its input changes. It's the rate at which the function's value changes with respect to change in the variable. The derivative of a function f(x) at a point x = a is given by:
f′(a)=limh→0hf(a+h)−f(a)
This formula is essentially the limit of the average rate of change as the interval shrinks to zero.
2.0Left hand Limits and Right Hand limit of a Function
limx→a−f(x)=Llimx→a+f(x)=L
limx→af(x)=L
If limx→a−f(x)=limx→a+f(x)=L( finite )
Geometrical Meaning:
Tangent to the curve y = f(x) at a points (a, f(a)) is a limiting case of slope of secant through A.
limB→AmAB=limh→0hf(a+h)−f(a)
limC→AmAc=limh→0−hf(a−h)−f(a)
Derivative exists if
limh→0−hf(a−h)−f(a)=limh→0hf(a+h)−f(a)
3.0Limits and Derivatives Formulas
Algebra of Limits:
limx→ac=c, where c is a constant.
limx→ax=a
limx→a[f(x)±g(x)]=limx→af(x)±limx→ag(x)
limx→a[f(x)⋅g(x)]=limx→af(x)⋅limx→ag(x)
limx→ag(x)f(x)=limx→ag(x)limx→af(x)
limx→a[(f)(x)]=limx→af(x)
Limits of Some Basic Trigonometric Functions
limx→0xsinx=1
limx→0xtanx=1
limx→0xsin−1x=1
limx→0xtan−1x=1(Where x is measured in radians)
If limx→0f(x)=0thanlimx→0f(x)sinf(x)=1e.g. limx→1(lnx)sin(lnx)=1
limx→0x1−cosx=0
Limits of Some Exponential and Logarithmic Functions
1.0What are Limits and Derivatives in Mathematics?
2.0Left hand Limits and Right Hand limit of a Function
3.0Limits and Derivatives Formulas
1.0Relationship Between Derivatives and Limits
The concept of derivatives is fundamentally built on the concept of limits. A derivative is essentially a limit that describes the rate of change of a function at a specific point. Without limits, the definition of a derivative wouldn't exist. When we calculate a derivative using the definition, we're actually finding the limit of the function's average rate of change as the interval over which the change is measured approaches zero.
2.0Solved Examples of Limits and Derivatives
Example 1: Evaluate the limit: limx→3x−3x2−9
Solution:
Given: limx→3x−3x2−9
=limx→3x−3x2−9
Simplify the expression
=limx→3x−3(x−3)(x+3)
Cancelling the common factor (x – 3)
=limx→3x+3
Now, substitute x = 3 into the simplified expression
= 3 + 3 = 6
So, limx→3x−3x2−9=6
Example 2: Find the derivative of f(x) = x2 at x = 2.
Solution:
Using the definition of a derivative:
f′(x)=limh→0hf(x+h)−f(x)
Substituting f(x) = x2:
f′(2)=limh→0h(2+h)2−4
f′(2)=limh→0h4+4h+h2−4
f′(2)=limh→0(4+h)
f′(2)=4
So, f'(2) = 4.
Example 3: Evaluate the limit: limx→2x−2x2−4
Solution:
Given: limx→2x−2x2−4
=limx→2x−2x2−4
Simplify the expression
=limx→2x−2(x−2)(x+2)
Cancelling the common factor (x – 2)
=limx→2x+2
Now, substitute x = 2 into the simplified expression
= 2 + 2 = 4
So, limx→2x−2x2−4=4
Example 4: Find the derivative of f(x) = 3x3 – 5x2 + 2x – 7.
Solution:
Using the power rule dxd[xn]=nxn−1, differentiate each term:
f′(x)=3⋅3x2−5⋅2x1+2⋅1x0−0
f′(x)=9x2−10x+2
Example 5: Find the derivative of f(x) = x2 + 3x using the definition of a derivative.
Solution:
The derivative is given by:
f′(x)=limh→0hf(x+h)−f(x)
Substitute f(x) = x2 + 3x:
Expand and simplify:
f′(x)=limh→0h(x+h)2+3(x+h)−(x2+3x)
f′(x)=limh→0h2xh+h2+3h
Factor out h:
f′(x)=limh→0(2x+h+3)
f′(x)=2x+3
So, the derivative is f'(x) = 2x + 3.
Example 6: Evaluate the limit limx→∞3x3+x−75x3−2x2+4
Solution:
Given: limx→∞3x3+x−75x3−2x2+4
Divide each term by x3 (the highest power of x in the denominator)
limx→∞3+x21−x375−x2+x34
Putting the limit x = infinite
limx→∞3+x21−x375−x2+x34=35
So, limx→∞3x3+x−75x3−2x2+4=35
Example 7: Evaluate limx→0{x1+x−1−x}
Solution:
We have
limx→0{x1+x−1−x}
=limx→0{x1+x−1−x⋅(1+x+1−x)(1+x+1−x)}
=limx→0x(1+x+1−x){(1+x)−(1−x)}
=limx→0x(1+x+1−x)2x
=limx→0(1+x+1−x)2=1 [puttingx=0]
Example 8: Evaluate limx→1(x−1)(x2−4x+3)
Solution:
We have,
limx→1(x−1)(x2−4x+3)
=limx→1(x−1)(x−1)(x−3)
=limx→1(x−3)
=-2
Example 9: Evaluate limx→0(xe3x−1)
Solution:
We have,
limx→0(xe3x−1)
=lim3x→0{(3xe3x−1)×3}
[∵(x→0)⇒(3x→0)]
=3×limy→0(yey−1) , where y = 3x
= (3 × 1) = 3 [⊠limy→0(yey−1)=1]
Example 10: Evaluate limx→0(x3x−2x)
Solution:
We have,
limx→0(x3x−2x)
=limx→0{x(3x−1)−(2x−1)}
limx→0(x3x−1)−limx→0(x2x−1)
= (log 3 – log 2)
=log23[limx→0(xax−1)=loga].
Example 11: Find the derivative of f(x)=sin(x)⋅cos(x).
Solution:
This is a product of two functions, so use the product rule:
f′(x)=dxd[sin(x)⋅cos(x)]
f′(x)=sin(x)⋅dxd[cos(x)]+cos(x)⋅dxd[sin(x)]
f′(x)=sin(x)⋅(−sin(x))+cos(x)⋅cos(x)
f′(x)=−sin2(x)+cos2(x)
Example 12: Find the derivative of f(x) = e3x.
Solution:
Given: f(x) = e3x
Use the chain rule:
f′(x)=dxd[e3x]
f′(x)=e3x⋅dxd[3x]
f′(x)=3e3x
Example 13: Find the derivative of f(x)=ln(2x2+3x).
Solution:
Given: f(x)=ln(2x2+3x)
Apply the chain rule:
f′(x)=2x2+3x1⋅dxd[2x2+3x]
f′(x)=2x2+3x1⋅(4x+3)
Simplify:
f′(x)=2x2+3x4x+3
3.0Practice Questions of Limits and Derivatives
limx→3(x+3x2+9)
limx→21(2x−14x2−1)
limx→0(xe4x−1)
Find the derivative of f(x) = 7x4 – 3x2 + 5x – 9.
Find the derivative of g(x)=x+x1 .
Find the derivative of f(x) = sin(3x).
Find the derivative of g(x) = tan(x)·sec(x).
Find the derivative of f(x)=e2x⋅ln(x).
Find the derivative of g(x)=log10(x2+1).
Answers:
3
2
4
f’(x) = 28x3 − 6x + 5
g′(x)=1−x21
f’(x) = 3 cos (3x)
g’(x) = sec3 (x) + sec (x). tan2 (x)
f′(x)=e2x(2ln(x)+x1)
g′(x)=(x2+1)ln(10)2x
4.0Sample Questions on Limits and Derivatives
What are limits in mathematics?
Ans: A limit in mathematics describes the value that a function approaches as the input (or variable) approaches a certain point. For instance, if we say limx→af(x)=L, it means that as x gets closer to a, the function f(x) gets closer to the value L.
How are limits and derivatives related?
Ans: The concept of a derivative is built on the idea of limits. The derivative of a function at a point is defined as the limit of the average rate of change of the function as the interval approaches zero. Mathematically, it's expressed as f′(x)=limh→0hf(x+h)−f(x).
How do you find the derivative of a function using the limit definition?
Ans: To find the derivative of a function using the limit definition, you calculate:
f′(x)=limh→0hf(x+h)−f(x)
This formula calculates the slope of the secant line as the interval h approaches zero, effectively giving the slope of the tangent line at point x.
A limit exists only if the left-hand limit and right-hand limit are equal.
Continuity implies that the function has no break at the given point.
The derivative represents the slope of the tangent to the curve.
Differentiation measures the instantaneous rate of change.
Limits form the foundation for the definition of derivatives.
3.0High Weightage Topics
Topic
JEE Importance
Difficulty Level
Standard Limits
Very High
Moderate
Evaluation of Limits
Very High
Moderate
Left-Hand & Right-Hand Limits
High
Moderate
Continuity
High
Moderate
Definition of Derivative
Very High
Moderate
Basic Differentiation
Very High
Moderate
Mixed Calculus Problems
Very High
Moderate–High
4.0Formula Handbook
The following formulas and standard results are essential for solving questions from Limits and Derivatives in JEE Main, JEE Advanced, and CBSE examinations.
Formula / Standard Result
Expression
Definition of Derivative
(f′(x)=h→0limhf(x+h)−f(x))
Derivative of Constant
(dxd(c)=0)
Derivative of (x)
(dxd(x)=1)
Power Rule
(dxd(xn)=nxn−1)
Sum/Difference Rule
(dxd[f(x)±g(x)]=f′(x)±g′(x))
Constant Multiple Rule
(dxd[cf(x)]=cf′(x))
Standard Limit
(x→0limxsinx=1)
Standard Limit
(x→0limxtanx=1)
Standard Limit
(x→0limx21−cosx=21)
Standard Limit
(x→0limxex−1=1)
Standard Limit
(x→0limxax−1=lna,;a>0)
5.0Common Mistakes & JEE Tips
Limits and Derivatives is the gateway to Calculus and requires strong conceptual understanding. Most errors occur due to incorrect application of standard limits, improper algebraic simplification, or confusion while using the definition of the derivative.
Common Mistake
Correct Approach
Directly substituting values in indeterminate forms
Simplify the expression first using algebraic techniques or standard limits.
Confusing Left-Hand Limit (LHL) and Right-Hand Limit (RHL)
Check both limits separately before concluding whether the limit exists.
Forgetting standard limit formulas
Memorize the most frequently used limits for quick evaluation.
Using the derivative formula incorrectly
Apply the definition carefully by substituting (f(x+h)) correctly.
Errors in algebraic simplification
Factorize, rationalize, or cancel common terms before taking limits.
Missing negative signs during differentiation
Differentiate step by step and verify signs carefully.
Confusing continuity with differentiability
A function may be continuous but not differentiable at a point.
Ignoring domain restrictions
Ensure the function is defined near the point where the limit is evaluated.
6.0ALLEN Faculty Tips
Memorize all standard limit results thoroughly.
Practice algebraic simplification techniques such as factorization and rationalization.
Learn the derivative definition conceptually before memorizing formulas.
Understand the graphical meaning of limits and derivatives.
Revise basic differentiation rules regularly.
Focus on conceptual clarity instead of rote learning.
Solve Previous Years' Questions (PYQs) to understand the JEE examination pattern.
7.0PYQ Trend Analysis
Limits and Derivatives is one of the most important introductory Calculus chapters in JEE Main and JEE Advanced. Questions are commonly asked on standard limits, evaluation of limits, continuity, the definition of derivatives, and basic differentiation.
Note: The trend below is based on the analysis of previous years' JEE Main and JEE Advanced question papers. The exact number of questions may vary each year.
Topic
Questions Asked (Last 5 Years)
Average Difficulty
Standard Limits
2–3
Moderate
Evaluation of Limits
2–4
Moderate
Left-Hand & Right-Hand Limits
1–2
Moderate
Continuity
1–2
Moderate
Definition of Derivative
2–3
Moderate
Basic Differentiation
2–4
Moderate
Mixed Calculus Problems
2–4
Moderate–High
8.0Most Common Question Types
Evaluating limits using standard limit formulas.
Solving indeterminate forms through algebraic simplification.
Comparing Left-Hand Limit (LHL) and Right-Hand Limit (RHL).
Checking the continuity of a function at a point.
Finding derivatives using the first principle (definition).
Applying basic differentiation rules.
Solving introductory Calculus problems involving limits and derivatives.
JEE Advanced questions based on conceptual understanding of Calculus.
9.0Smart Revision Strategy
Follow this revision sequence to master the chapter efficiently:
Revise the concept of limits and standard limit formulas.
Practice evaluating limits using factorization, rationalization, and substitution techniques.
Understand the difference between LHL, RHL, and continuity.
Learn the definition of the derivative from first principles.
Memorize the basic rules of differentiation.
Solve introductory derivative problems.
Practice Previous Years' Questions (PYQs).
Finish with mixed Calculus problems under timed conditions.