Question

P(x)=2x^3-11x^2+ax-40 if x+4 is a factor of this polynomial what is the value of a

Answer 1

a = -86.

Explanation:

By the Factor Theorem, if x + 4 is a factor then P(-4) = 0, so:

P(-4) = 2(-4)^3 - 11(-4)^2 + a(-4)- 40 = 0

-128 - 176 - 4a - 40 = 0

-4a = 128 +176 + 40

-4a = 344

a = -86.