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Polynomials Notes: Class 10 Maths Chapter 2

Class 10 Maths Chapter 2 Polynomials covers the geometrical meaning of zeroes of a polynomial, the relationship between zeroes and coefficients, and division of polynomials.

Overview of Topics & Subtopics (Click to Jump)

1. Geometrical Meaning of the Zeroes of a Polynomial

Short Note:

• The zeroes of a polynomial p(x) are the x-coordinates of the points where the graph of y = p(x) intersects the x-axis.

• A linear polynomial has at most 1 zero, a quadratic has at most 2, and a cubic has at most 3 zeroes — in general, a polynomial of degree n has at most n zeroes.

2. Relationship between Zeroes and Coefficients

Short Note:

• For a quadratic polynomial ax² + bx + c with zeroes α and β: Sum of zeroes α + β = −b/a; Product of zeroes αβ = c/a.

• For a cubic polynomial ax³ + bx² + cx + d with zeroes α, β, γ: α+β+γ = −b/a; αβ+βγ+γα = c/a; αβγ = −d/a.

3. Division Algorithm for Polynomials

Short Note:

• If p(x) and g(x) are polynomials with g(x) ≠ 0, then there exist polynomials q(x) and r(x) such that p(x) = g(x) · q(x) + r(x), where r(x) = 0 or degree of r(x) < degree of g(x).

• This is used to check if one polynomial is a factor of another, or to find remaining zeroes when some zeroes are already known.

NCERT Textbook Exercise Questions

Find the zeroes of the quadratic polynomial x² + 7x + 10, and verify the relationship between zeroes and coefficients.
Answer: x²+7x+10 = (x+2)(x+5), so zeroes are −2 and −5. Sum = −7 = −b/a = −7/1 ✓. Product = 10 = c/a = 10/1 ✓.
Find a quadratic polynomial whose sum and product of zeroes are ¼ and −1 respectively.
Answer: A quadratic polynomial is k[x² − (sum)x + (product)] = k[x² − ¼x − 1], e.g. taking k = 4 gives 4x² − x − 4.
Divide 3x² − x³ − 3x + 5 by x − 1 − x², and verify the division algorithm.
Answer: Arranging in standard form and dividing: p(x) = (−x²+x−1)(x−2) + 3, giving quotient (x − 2) and remainder 3, i.e. p(x) = g(x)·q(x) + r(x) as required.
If two zeroes of the polynomial x&sup4; − 6x³ − 26x² + 138x − 35 are 2 ± √3, find the other zeroes.
Answer: Since 2+√3 and 2−√3 are zeroes, (x² − 4x + 1) is a factor. Dividing the given polynomial by this factor gives quotient x² − 2x − 35 = (x−7)(x+5), so the other two zeroes are 7 and −5.
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Class 10 › Mathematics › Polynomials
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Topics in this chapter: Geometrical Meaning of the Zeroes of a PolynomialRelationship between Zeroes and CoefficientsDivision Algorithm for Polynomials