Question

Let P(x)=kx^(3)-9x^(2)-15x+50.
(a) If 2x+5 is a factor of P(x), find the value of k.
(b) Factorize P(x) completely.

Answer 1

If 2x+5 is a factor of P(x)
Then P(-5/2) = k(-5/2)^(3)-9(-5/2)^(2)-15(-5/2)+50 =0
Find k..

Answer 2

You can equate to zero because its a factor of P(x), then -5/2 as value for x