Exercise 2.4 is the Long Answer set of NCERT Exemplar Class 10 Maths Chapter 2 Polynomials. It has 9 questions (Q34 to Q42) that test three connected skills. You build a quadratic from a given sum and product of zeroes, use the division algorithm to factorise cubics and quartics, and find the remaining zeroes when one is already known. All solutions follow the 2026-27 CBSE syllabus.

  • 9 Long Answer questions - Q34 to Q42 - the hardest set in the Polynomials Exemplar.
  • Key skills: building a quadratic from zeroes, the division algorithm p(x) = g(x) · q(x) + r(x), and finding the remaining zeroes of a cubic or quartic.

Each solution here is written by subject experts, mapped to the 2026-27 rationalised NCERT, and checked against CBSE board paper patterns.

NCERT Exemplar Solutions Class 10 Maths Chapter 2 Polynomials Exercise 2.4
Solved by Collegedunia - Every solution below follows the CBSE marker checklist: build the polynomial, apply the division algorithm or known-factor trick, verify the zeroes against the coefficient relations, and state a boxed final answer.

What Polynomials Exercise 2.4 Covers in Class 10 Maths

Exercise 2.4 is the Long Answer set of Chapter 2. It has 9 questions (Q34 to Q42), the most demanding in the chapter. Each one either builds a polynomial from its zeroes or uses the division algorithm to find hidden zeroes.

  • Q34 to Q37: build a quadratic from a given sum S and product P of zeroes, then find the zeroes by factorisation. Questions involve fractional, surd and rationalised coefficients.
  • Q38: a cubic whose zeroes are in arithmetic progression (AP form a, a+b, a+2b) - use sum and product to find the actual zeroes.
  • Q39: a cubic with one known zero - divide out the factor, then factorise the resulting quadratic.
  • Q40: find k so that a given quadratic is a factor of a quartic - set the remainder to zero after long division.
  • Q41: a cubic with a known linear factor - divide out and solve the quotient with the quadratic formula.
  • Q42: find a and b so that all zeroes of a cubic are also zeroes of a degree-5 polynomial, and identify the extra zeroes.

This set builds on the coefficient relations from Exercise 2.3 and adds the Division Algorithm. Do it cleanly, and the chapter's board-level long answers feel routine.

Key Formulas

Every question here uses one or more of the four formulas below. Keep them on your rough sheet before you start.

ConceptFormulaWhen to use
Build quadratic from zeroes k[x2 - Sx + P] Q34, Q35, Q36, Q37 - given sum S and product P
Zeroes of quadratic ax2+bx+c α + β = -ba,   αβ = ca All questions - verification step
Zeroes of cubic ax3+bx2+cx+d α+β+γ = -ba,   αβ+βγ+γα = ca,   αβγ = -da Q38, Q39, Q41, Q42
Division algorithm p(x) = g(x) · q(x) + r(x) Q39, Q40, Q41, Q42 - divide out a known factor

Important: When building a quadratic from fractional S or P, always multiply by the LCM of denominators to get integer coefficients before factorising. The zeroes stay the same.

Building a Quadratic from Sum and Product of Zeroes

Questions Q34 to Q37 all start from a given sum S and product P. This three-step routine gets full marks every time. Memorise the order.

  1. Write the standard form: x2 - Sx + P. Substitute S and P directly - handle the double minus if S is negative.
  2. Scale to clear fractions: multiply by the LCM of all denominators. This does not change the zeroes. For surd denominators (Q37), rationalise first.
  3. Factorise and read zeroes: split the middle term, group, read the zeroes. Then verify: substitute back into α + β = -b/a and αβ = c/a using the original coefficients.

Topic-wise Breakdown

The 9 questions split cleanly into three types. Practise each type as a block before mixing them.

Question(s)TypeKey TechniqueDifficulty
Q34, Q35Build quadratic (fractional S, P)Scale by LCM; split-the-middle; verifyMedium
Q36Build quadratic (surd S, P)Double-minus handling; surd splitMedium
Q37Build quadratic (rationalise + surd)Rationalise S first; scale by 10; surd splitHard
Q38Cubic with AP zeroesAP middle-zero trick; product equation in bHard
Q39Cubic with one known zeroDivide by (x - \sqrt{2}); split quotient quadraticHard
Q40Find k so quadratic divides quarticLong division; remainder = 0; two conditions agreeVery Hard
Q41Cubic with known linear factorDivide out factor; quadratic formula for remainderHard
Q42Shared zeroes of cubic and quinticForce remainder 0 with two unknowns; identify extra zeroesVery Hard

All Exercise 2.4 Solutions with Step-by-Step Answers

IV. Long Answer Questions (Exercise 2.4)

Q 2.1

Find a quadratic polynomial whose sum and product of zeroes are -83 and 43 respectively. Also find the zeroes by factorisation.

Q 2.2

Find a quadratic polynomial whose sum and product of zeroes are 218 and 516 respectively. Also find the zeroes by factorisation.

Q 2.3

Find a quadratic polynomial whose sum and product of zeroes are -23 and -9 respectively. Also find the zeroes by factorisation.

Q 2.4

Find a quadratic polynomial whose sum and product of zeroes are -325 and -12 respectively. Also find the zeroes by factorisation.

Q 2.5

Given that the zeroes of the cubic polynomial x3-6x2+3x+10 are of the form a, a+b, a+2b for some real numbers a and b, find the values of a and b as well as the zeroes of the given polynomial.

Q 2.6

Given that 2 is a zero of the cubic polynomial 6x3+2 x2-10x-42, find its other two zeroes.

Q 2.7

Find k so that x2+2x+k is a factor of 2x4+x3-14x2+5x+6. Also find all the zeroes of the two polynomials.

Q 2.8

Given that x-5 is a factor of the cubic polynomial x3-35 x2+13x-35, find all the zeroes of the polynomial.

Q 2.9

For which values of a and b are the zeroes of q(x)=x3+2x2+a also the zeroes of the polynomial p(x)=x5-x4-4x3+3x2+3x+b? Which zeroes of p(x) are not the zeroes of q(x)?

Polynomials Exemplar: Other Exercises & Resources

Work through the rest of the Polynomials Exemplar, then pair it with the matching study resources for Chapter 2.

ResourceWhat it coversOpen
Exercise 2.4Long-answer build-from-zeroes and division-algorithm problems, solved step by step.This page
Exercise 2.1MCQs on zeroes, coefficients and reading quadratic graphs.Exemplar Exercise 2.1
Exercise 2.2True/false reasoning on quotient, remainder and degree.Exemplar Exercise 2.2
Exercise 2.3Short-answer factorisation and zero-coefficient verification.Exemplar Exercise 2.3
Exemplar Solutions (full chapter)All four exercises of the Polynomials Exemplar in one place.Chapter 2 Exemplar Solutions
NCERT SolutionsStep-by-step answers to every textbook question, with an Expert view.Chapter 2 NCERT Solutions
NotesConcept-first revision notes on zeroes, relations and the division algorithm.Chapter 2 Notes
Formula SheetOne-page list of the key zero-coefficient and division relations.Chapter 2 Formula Sheet

Student Feedback

In a Collegedunia poll of 9,840 Class 10 Maths students before the 2026 boards, 78% said Q38 (AP zeroes of a cubic) and Q42 (shared zeroes of two polynomials) were the hardest in Exercise 2.4. They lost marks by forgetting the AP trick (middle zero = sum/3) or the zero-coefficient placeholder during division. Students who practised both routines picked up full marks.

Source: Collegedunia Class 10 Mathematics student poll. Sample of 9,840 students from CBSE schools across 12 states.

Other Resources for Polynomials Class 10 Maths

Pair this with the other Class 10 Maths resources for Polynomials, all linked below.

Frequently Asked Questions on Exercise 2.4

Ques. How many questions are there in NCERT Exemplar Class 10 Maths Chapter 2 Exercise 2.4?

Ans. Exercise 2.4 has 9 Long Answer questions, numbered Q34 to Q42 in the NCERT Exemplar book. It is the most difficult exercise in Chapter 2 Polynomials and covers building a quadratic from given zeroes, the division algorithm, and finding remaining zeroes of a cubic or quartic polynomial when one zero is already known.

Ques. What is the AP zeroes trick used in Q38 of Exercise 2.4?

Ans. When the three zeroes of a cubic are in arithmetic progression, say a, a+b, a+2b, their sum equals 3(a+b). This means the middle zero a+b is always equal to (sum of zeroes)/3. For Q38, the cubic is x³ - 6x² + 3x + 10, so the sum of zeroes is 6, and the middle zero is immediately 2. This shortcut converts what looks like a two-variable system into a single-variable equation for b. Students who know this trick finish Q38 in under two minutes.

Ques. Why do we need to insert a 0x placeholder in Q42 when dividing by q(x)?

Ans. In Q42, q(x) = x³ + 2x² + a has no x term. During polynomial long division, every term of the divisor must occupy its own column. If you write q(x) = x³ + 2x² + a without a column for 0x, the subtraction in each step shifts by one position and every subsequent remainder is wrong. Always write q(x) as x³ + 2x² + 0x + a to keep the alignment correct. This is the most common reason students get the wrong value of a in Q42.

Ques. Is NCERT Exemplar Exercise 2.4 important for CBSE Class 10 board exams?

Ans. Yes. The division algorithm (p(x) = g(x)q(x) + r(x)) is a standard topic in the Class 10 CBSE Maths syllabus for 2026-27, and Long Answer questions based on it appear regularly in board papers. Questions similar to Q38 (AP zeroes) and Q40 (finding k so a quadratic is a factor) have appeared in CBSE board sample papers. Students who can do Exercise 2.4 correctly are well placed for the 4-5 mark questions in the Algebra section of the board paper.

Ques. How is Exercise 2.4 different from Exercise 2.3 in the NCERT Exemplar?

Ans. Exercise 2.3 (Short Answer, Q24 to Q33) asks students to find zeroes by factorisation and verify the zeroes-coefficients relations for polynomials that are given directly. Exercise 2.4 (Long Answer, Q34 to Q42) is harder: Q34 to Q37 reverse the process (build the polynomial from the zeroes), and Q38 to Q42 use the division algorithm to find hidden zeroes or unknown coefficients. The two exercises together cover the full range of polynomial skills the CBSE Maths board paper tests in Chapter 2.