Question

If −1 is a zero of the polynomial p(x)=ax^3−x^2+x+4, find the value of a.

Answer 1

a = 2

Explanation:

given x = - 1 is a zero then f(- 1) = 0 , that is

a(- 1)³ - (- 1)² - 1 + 4 = 0

- a - 1 - 1 + 4 = 0

- a + 2 = 0 ( subtract 2 from both sides )

- a = - 2 ( multiply both sides by - 1 )

a = 2