How do you write a polynomial with zeros 1,-4, 5?

1 Answer
Feb 22, 2016

Polynomial is (x-1)(x+4)(x-5)(x1)(x+4)(x5)
or x^3-2x^2-19x+20x32x219x+20

Explanation:

A polynomial (say with xx as variable) with zeros 1,-4, 5, means that when xx is put equal to either 11 , -44 or 55, its value reduces to zero.

Hence the polynomial would be (x-1)(x+4)(x-5)(x1)(x+4)(x5)

or (x-1)(x^2+4x-5x-20)(x1)(x2+4x5x20) (multiplying last two factors)

or (x-1)(x^2-x-20)(x1)(x2x20)

or x^3-x^2-20x-x^2+x+20x3x220xx2+x+20 or

x^3-2x^2-19x+20x32x219x+20