📐 CBSE · Class 10 · Mathematics · Chapter 4

Quadratic
Equations

Complete chapter resources for CBSE Class 10 Mathematics — topic breakdown, key formulas, sample questions, previous year board questions, and instant AI question paper generation.

4Topics
6–8Board marks
8Sample questions
3PYQ included

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Key Formulas — Chapter 4
  • Standard form: ax² + bx + c = 0, a ≠ 0
  • Quadratic formula: x = (−b ± √(b²−4ac)) / 2a
  • Discriminant: D = b² − 4ac
  • Sum of roots: α + β = −b / a
  • Product of roots: αβ = c / a
  • Equal roots condition: D = 0 ⟹ b² = 4ac

What this chapter covers

A quadratic equation in one variable is a polynomial equation of degree 2, written in the standard form ax² + bx + c = 0, where a, b, c are real numbers and a ≠ 0. The solutions — values of x that satisfy the equation — are called roots or zeroes of the quadratic. NCERT Chapter 4 begins by defining this standard form, distinguishing quadratic equations from linear and higher-degree polynomials, and practising the skill of representing real-world situations as quadratic equations before attempting to solve them.

The chapter teaches four approaches to finding roots: recognising roots by inspection, factorising by splitting the middle term (product-sum method), transforming the equation by completing the square, and applying the quadratic formula — also known as Sridharacharya's formula — x = (−b ± √D) / 2a. A central unifying concept is the discriminant D = b² − 4ac, which determines the nature of roots: two distinct real roots when D > 0, two equal real roots when D = 0, and no real roots when D < 0.

Board questions consistently include word problems where a real-world scenario — involving speed and distance, areas of rectangles, time-and-work rates, or age relationships — must first be modelled as a quadratic equation, solved, and then interpreted in context. These application problems typically carry the highest marks in the chapter and demand both algebraic accuracy and careful reading of the problem setup.

What's inside Chapter 4

As per NCERT Class 10 Mathematics (CBSE syllabus)

Topic 1
Standard Form of Quadratic Equations
Definition: ax² + bx + c = 0, a ≠ 0. Identifying quadratic equations from a list of polynomial expressions. Representing real-world word problems as quadratic equations before solving.
Topic 2
Solution by Factorisation
Splitting the middle term using the product-sum method. Finding a factor pair of ac that adds up to b, then applying the zero-product property to obtain both roots.
Topic 3
Solution by Completing the Square & Quadratic Formula
Transforming ax² + bx + c into a perfect-square form to isolate x. This algebraic manipulation directly derives Sridharacharya's formula x = (−b ± √D) / 2a, applicable to all quadratics.
Topic 4
Nature of Roots — Discriminant
D = b² − 4ac reveals root type without full computation. D > 0: two distinct real roots. D = 0: two equal real roots. D < 0: no real roots. High-frequency board topic for finding unknown coefficients.

How this chapter fits in

Useful for setting question difficulty and cross-chapter papers.

Builds on
Ch 2 · Polynomials
Factorisation of quadratics, zeroes of a polynomial, relationship between roots and coefficients
Ch 3 · Linear Equations in Two Variables
Algebraic manipulation — substitution, elimination, and modelling real-life scenarios as equations
Chapter 4 Quadratic
Equations
Leads to
Ch 5 · Arithmetic Progressions
Finding which term equals a value or the number of terms can reduce to a quadratic equation
Class 11 · Algebra
Complex roots, quadratic inequalities, conic sections, and further applications in calculus

Marks & question-type breakdown

Typical pattern based on CBSE Class 10 board papers from the last five years.

Question type Marks Typical count What's usually tested
MCQ / Objective 1 1–2 Discriminant value, nature of roots, or identifying whether an equation is quadratic
Very Short Answer 2 1 Find roots by factorisation, check nature of roots, or find k for equal roots
Short Answer 3 1 Completing the square or a straightforward word problem modelled as a quadratic
Long Answer / Word Problem 4–5 1 Real-life application — speed-distance, area, work-rate, or age problems
Total (approximate) 6–8 4–5 Weightage varies across paper sets and years

8 sample questions — generated by MarksZen AI

Aligned to CBSE Class 10 Mathematics Chapter 4. Covers all question types across Easy, Medium, and Hard difficulty.

Q1 Easy 1 mark MCQ
The discriminant of the quadratic equation 3x² − 2x + 1/3 = 0 is: (a) 0 (b) 4 (c) −4 (d) 8
Q2 Easy 2 marks Short Answer
Find the roots of the quadratic equation x² − 5x + 6 = 0 by the method of factorisation.
Q3 Medium 2 marks Short Answer
For what value(s) of k does the equation 2x² + kx + 8 = 0 have two equal real roots?
Q4 Medium 3 marks Short Answer
Find the roots of 2x² + x − 4 = 0 by the method of completing the square.
Q5 Medium 3 marks Word Problem
Find two consecutive odd positive integers whose sum of squares is 290. Form a quadratic equation and solve by factorisation.
Q6 Hard 4 marks Word Problem
The diagonal of a rectangular field is 60 metres more than the shorter side. If the longer side is 30 metres more than the shorter side, find the sides of the field.
Q7 Hard 4 marks Word Problem
Two water taps together can fill a tank in 9⅜ hours. The tap with the larger diameter takes 10 hours less than the smaller one to fill the tank separately. Find the time in which each tap can fill the tank separately.
Q8 Hard 5 marks Case-Based
A motor boat whose speed is 18 km/h in still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot. (i) Let the speed of the stream be x km/h. Form a quadratic equation in x. (ii) Solve the equation to find the speed of the stream. (iii) Hence find the total time taken for the entire journey of 48 km (24 km each way).
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From CBSE board examinations

Actual questions from past Class 10 Mathematics board papers — Quadratic Equations chapter.

Board 20232 marks
Find the roots of √2 x² + 7x + 5√2 = 0 by the method of factorisation. (All India 2023)
Board 20222 marks
Find the value of k for which the quadratic equation kx(x − 2) + 6 = 0 has two equal roots. (Delhi 2022)
Board 20203 marks
A train travels 360 km at a uniform speed. If the speed had been 5 km/h more, it would have taken 1 hour less for the same journey. Form a quadratic equation and find the speed of the train. (CBSE 2020)

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Questions teachers ask

How many marks does Quadratic Equations carry in the CBSE Class 10 board exam? +
Typically 6–8 marks across 3–4 questions — one 1-mark MCQ, one 2-mark short answer, and one 3–5 mark word problem. The exact weightage varies by year and paper set, but this chapter has appeared in every CBSE Class 10 Maths board paper for the last decade.
Should students use factorisation or the quadratic formula in exams? +
Both are equally accepted in CBSE exams. Factorisation is faster when the roots are rational integers. The quadratic formula (Sridharacharya's formula) always works and is the safer choice for irrational or non-obvious roots. Students should know both methods confidently.
What is the discriminant and when do board questions focus on it? +
The discriminant D = b² − 4ac reveals the nature of roots without fully solving the equation. High-probability board questions set D = 0 and ask students to find k for equal roots, or ask whether roots are real by checking if D ≥ 0. These are typically 2-mark questions and appear almost every year.
Are Vieta's formulas (sum and product of roots) in the CBSE Class 10 syllabus? +
Yes. The NCERT textbook covers α + β = −b/a and αβ = c/a under the "Relationship between roots and coefficients" section. They appear in questions like "one root is twice the other" where students set up and solve a pair of equations using these identities.
How do I generate a custom question paper for Quadratic Equations using MarksZen? +
Sign up for a free MarksZen account, choose CBSE Class 10 Mathematics, select Chapter 4 (Quadratic Equations), set your preferred question-type mix and total marks — the AI generates a complete board-aligned paper with answer key in under 2 minutes, ready for PDF export.