UP Board Class 10 Maths NCERT Solutions: Chapter 2 Polynomials

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UP Board Class 10 Maths NCERT Solutions: Chapter 2 Polynomials 2025-26 – All Questions

UP Board Class 10 Maths NCERT Solutions: Chapter 2 Polynomials 2025-26 – All Questions

Introduction to Polynomials

Chapter 2 of NCERT Class 10 Maths, Polynomials, is a crucial chapter for UP Board 2025-26 exams, contributing 7–10 marks in algebra. It covers zeros of polynomials, the relationship between zeros and coefficients, the division algorithm, and polynomial formation. This post provides copyright-free, step-by-step solutions to all 18 NCERT exercise questions (Exercises 2.1–2.4), rephrased to ensure originality, to help you master UP Board Class 10 Maths. Practice these questions to excel in your board exams!

Exercise 2.1: Graphical Representation of Polynomials

Question 1

Find the number of zeros of the polynomial p(x) = x² – 4x + 3.

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Solution:

The number of zeros is the number of times the graph of p(x) intersects the x-axis.

  • Given: p(x) = x² – 4x + 3 (quadratic, degree 2).
  • Factorize: x² – 4x + 3 = (x – 1)(x – 3).
  • Roots: x = 1, x = 3.
  • Graph intersects x-axis at 2 points.

Answer: Number of zeros = 2.

Question 2

Find the number of zeros of the polynomial p(x) = x – 5.

Solution:

The number of zeros is the number of x-axis intersections.

  • Given: p(x) = x – 5 (linear, degree 1).
  • Root: x = 5.
  • Graph is a line intersecting x-axis at 1 point.

Answer: Number of zeros = 1.

Question 3

Find the number of zeros of the polynomial p(x) = 2x² + 8.

Solution:

The number of zeros is the number of x-axis intersections.

  • Given: p(x) = 2x² + 8 (quadratic, degree 2).
  • Discriminant: b² – 4ac = 0 – 4(2)(8) = –64 < 0.
  • No real roots, so the graph does not intersect x-axis.

Answer: Number of zeros = 0.

Question 4

Find the number of zeros of the polynomial p(x) = x³ – 2x².

Solution:

The number of zeros is the number of x-axis intersections.

  • Given: p(x) = x³ – 2x² (cubic, degree 3).
  • Factorize: x²(x – 2).
  • Roots: x = 0, x = 2.
  • Graph intersects x-axis at 2 points (double root at x = 0).

Answer: Number of zeros = 2.

Question 5

Find the number of zeros of the polynomial p(x) = x² – 6x + 9.

Solution:

The number of zeros is the number of x-axis intersections.

  • Given: p(x) = x² – 6x + 9 (quadratic, degree 2).
  • Factorize: (x – 3)².
  • Root: x = 3 (double root).
  • Graph touches x-axis at 1 point.

Answer: Number of zeros = 1.

Question 6

Find the number of zeros of the polynomial p(x) = 3.

Solution:

The number of zeros is the number of x-axis intersections.

  • Given: p(x) = 3 (constant, degree 0).
  • No variable, so no intersection with x-axis.

Answer: Number of zeros = 0.

Exercise 2.2: Zeros and Coefficients

Question 1

Find the zeros of the quadratic polynomial x² – 7x + 12 and verify the relationship between zeros and coefficients.

Solution:

For a quadratic polynomial ax² + bx + c, zeros are values where p(x) = 0. Sum of zeros = –b/a, product of zeros = c/a.

  • Given: p(x) = x² – 7x + 12 (a = 1, b = –7, c = 12).
  • Factorize: x² – 7x + 12 = x² – 4x – 3x + 12 = (x – 4)(x – 3).
  • Zeros: x = 3, x = 4.
  • Sum of zeros: 3 + 4 = 7 = –(–7)/1 = –b/a.
  • Product of zeros: 3 × 4 = 12 = 12/1 = c/a.
  • Relationships verified.

Answer: Zeros are 3 and 4. Sum = 7 = –b/a, Product = 12 = c/a.

Question 2

Form a quadratic polynomial whose zeros are 5 and –2.

Solution:

A quadratic polynomial with zeros α and β is x² – (α + β)x + αβ.

  • Zeros: α = 5, β = –2.
  • Sum of zeros: α + β = 5 + (–2) = 3.
  • Product of zeros: αβ = 5 × (–2) = –10.
  • Polynomial: x² – (3)x + (–10) = x² – 3x – 10.

Answer: The quadratic polynomial is x² – 3x – 10.

Exercise 2.3: Division Algorithm and Remainder Theorem

Question 1

Divide the polynomial 2x² + 7x + 3 by x + 2 and verify the division algorithm.

Solution:

The division algorithm states: Dividend = Divisor × Quotient + Remainder.

  • Divide 2x² + 7x + 3 by x + 2 using polynomial long division.
  • Step 1: 2x² ÷ x = 2x. Multiply: 2x(x + 2) = 2x² + 4x.
  • Subtract: (2x² + 7x + 3) – (2x² + 4x) = 3x + 3.
  • Step 2: 3x ÷ x = 3. Multiply: 3(x + 2) = 3x + 6.
  • Subtract: (3x + 3) – (3x + 6) = –3.
  • Quotient = 2x + 3, Remainder = –3.
  • Verify: 2x² + 7x + 3 = (x + 2)(2x + 3) + (–3).
  • Right side: (x + 2)(2x + 3) = 2x² + 3x + 4x + 6 = 2x² + 7x + 6. Add –3: 2x² + 7x + 6 – 3 = 2x² + 7x + 3, which matches the dividend.

Answer: Quotient = 2x + 3, Remainder = –3. Division algorithm verified.

Question 2

Divide the polynomial x³ – 5x² + 6x + 2 by x – 1 and find the quotient and remainder.

Solution:

Use polynomial long division.

  • Divide x³ – 5x² + 6x + 2 by x – 1.
  • Step 1: x³ ÷ x = x². Multiply: x²(x – 1) = x³ – x².
  • Subtract: (x³ – 5x² + 6x + 2) – (x³ – x²) = –4x² + 6x + 2.
  • Step 2: –4x² ÷ x = –4x. Multiply: –4x(x – 1) = –4x² + 4x.
  • Subtract: (–4x² + 6x + 2) – (–4x² + 4x) = 2x + 2.
  • Step 3: 2x ÷ x = 2. Multiply: 2(x – 1) = 2x – 2.
  • Subtract: (2x + 2) – (2x – 2) = 4.
  • Quotient = x² – 4x + 2, Remainder = 4.

Answer: Quotient = x² – 4x + 2, Remainder = 4.

Question 3

Check if x – 3 is a factor of the polynomial x³ – 7x² + 14x – 6.

Solution:

By the Factor Theorem, x – a is a factor of p(x) if p(a) = 0. Here, a = 3.

  • Given: p(x) = x³ – 7x² + 14x – 6.
  • Calculate p(3): 3³ – 7(3²) + 14(3) – 6 = 27 – 63 + 42 – 6 = 27 – 63 + 36 = 0.
  • Since p(3) = 0, x – 3 is a factor.

Answer: x – 3 is a factor.

Question 4

Find the remainder when the polynomial x³ – 4x² + 5x – 2 is divided by x – 2.

Solution:

By the Remainder Theorem, the remainder when p(x) is divided by x – a is p(a).

  • Given: p(x) = x³ – 4x² + 5x – 2, a = 2.
  • Calculate p(2): 2³ – 4(2²) + 5(2) – 2 = 8 – 16 + 10 – 2 = 0.

Answer: The remainder is 0.

Question 5

Find the remainder when the polynomial x⁴ – 3x² + 2x + 1 is divided by x + 1.

Solution:

By the Remainder Theorem, the remainder when p(x) is divided by x – a is p(a). Here, x + 1 = x – (–1), so a = –1.

  • Given: p(x) = x⁴ – 3x² + 2x + 1.
  • Calculate p(–1): (–1)⁴ – 3(–1)² + 2(–1) + 1 = 1 – 3 – 2 + 1 = –3.

Answer: The remainder is –3.

Exercise 2.4: Advanced Polynomial Problems

Question 1

Verify that 1 and 2 are zeros of the polynomial x³ – 3x² + 2x, and find the third zero.

Solution:

Verify zeros and use the sum of zeros for a cubic polynomial ax³ + bx² + cx + d, where sum = –b/a.

  • Given: p(x) = x³ – 3x² + 2x (a = 1, b = –3).
  • Verify x = 1: p(1) = 1³ – 3(1²) + 2(1) = 1 – 3 + 2 = 0. So, x = 1 is a zero.
  • Verify x = 2: p(2) = 2³ – 3(2²) + 2(2) = 8 – 12 + 4 = 0. So, x = 2 is a zero.
  • Sum of zeros: 1 + 2 + third zero = –(–3)/1 = 3.
  • Third zero = 3 – (1 + 2) = 0.
  • Verify x = 0: p(0) = 0 – 0 + 0 = 0. Confirmed.

Answer: Zeros are 1, 2, and 0.

Question 2

If two zeros of the polynomial x³ – 6x² + 11x – 6 are 2 and 3, find the third zero.

Solution:

For a cubic polynomial ax³ + bx² + cx + d, sum of zeros = –b/a.

  • Given: p(x) = x³ – 6x² + 11x – 6 (a = 1, b = –6).
  • Zeros: 2, 3, and third zero.
  • Sum of zeros: 2 + 3 + third zero = –(–6)/1 = 6.
  • Third zero = 6 – (2 + 3) = 1.
  • Verify: p(1) = 1³ – 6(1²) + 11(1) – 6 = 1 – 6 + 11 – 6 = 0. Confirmed.

Answer: The third zero is 1.

Question 3

Form a quadratic polynomial whose zeros are (3 + √2) and (3 – √2).

Solution:

A quadratic polynomial with zeros α and β is x² – (α + β)x + αβ.

  • Zeros: α = 3 + √2, β = 3 – √2.
  • Sum of zeros: α + β = (3 + √2) + (3 – √2) = 6.
  • Product of zeros: αβ = (3 + √2)(3 – √2) = 9 – 2 = 7.
  • Polynomial: x² – (6)x + 7 = x² – 6x + 7.

Answer: The quadratic polynomial is x² – 6x + 7.

Question 4

Form a quadratic polynomial whose zeros are –3/4 and 2/5.

Solution:

A quadratic polynomial with zeros α and β is x² – (α + β)x + αβ.

  • Zeros: α = –3/4, β = 2/5.
  • Sum of zeros: α + β = –3/4 + 2/5 = (–15 + 8)/20 = –7/20.
  • Product of zeros: αβ = (–3/4) × (2/5) = –6/20 = –3/10.
  • Polynomial: x² – (–7/20)x + (–3/10) = x² + (7/20)x – 3/10.
  • To avoid fractions, multiply by 20: 20x² + 7x – 6.

Answer: The quadratic polynomial is 20x² + 7x – 6.

Question 5

If the zeros of the polynomial x² – kx + 6 are in the ratio 2:3, find k.

Solution:

For a quadratic polynomial ax² + bx + c, sum of zeros = –b/a, product of zeros = c/a.

  • Given: p(x) = x² – kx + 6 (a = 1, b = –k, c = 6).
  • Product of zeros = 6/1 = 6.
  • Let zeros be 2m and 3m (ratio 2:3).
  • Product: 2m × 3m = 6m² = 6 → m² = 1 → m = ±1.
  • Case 1: m = 1. Zeros: 2, 3. Sum = 2 + 3 = 5 = –(–k)/1 = k.
  • Case 2: m = –1. Zeros: –2, –3. Sum = –2 – 3 = –5 = k.
  • Verify: For k = 5, zeros are 2, 3 (satisfies). For k = –5, zeros are –2, –3 (satisfies).

Answer: k = 5 or k = –5.

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