Chapter 2 · CBSE Class 10 Maths (NCERT)

Polynomials

Study the relationship between zeroes and coefficients of quadratic polynomials, and find polynomials from given zeroes.

📐 Chapter 2

2.1

Zeroes and Coefficients of a Quadratic

For ax²+bx+c with zeroes α and β: sum of zeroes=-b/a, product of zeroes=c/a.

1

Find the sum and product of zeroes of x²-5x+6.

sum=5, product=6 (matches roots 2,3)

2

Find the sum and product of zeroes of 2x²+3x-5.

sum=-3/2, product=-5/2

3

Find the sum and product of zeroes of 2x²-7x+3.

sum=7/2, product=3/2

2.2

Forming a Polynomial from Zeroes

A quadratic polynomial can be built from its zeroes using: x²-(sum of zeroes)x+(product of zeroes).

1

Find a quadratic polynomial with zeroes 3 and -2.

sum=1, product=-6; polynomial: x²-x-6

2

Find a quadratic polynomial with zeroes 1/2 and 1/3.

sum=5/6, product=1/6; polynomial: x²-5x/6+1/6, or 6x²-5x+1

3

Find a quadratic polynomial with zeroes -3 and 5.

sum=2, product=-15; polynomial: x²-2x-15

Practice

Exercises

1. Find the sum and product of zeroes of x²-7x+12.

2. Find the sum and product of zeroes of 3x²-2x-1.

3. Find a quadratic polynomial with zeroes 4 and -1.

4. Find a quadratic polynomial with zeroes 2/3 and -1.

5. If one zero of x²-8x+k is 3, find k.

6. Find the sum and product of zeroes of x²-9x+14.

7. Find the sum and product of zeroes of 4x²+5x-6.

8. Find a quadratic polynomial with zeroes 6 and -2.

9. Find a quadratic polynomial with zeroes 1/2 and -3.

10. If one zero of x²-11x+k is 7, find k.