Question

It is given that x+2 is a factor of P(x)=9x^(3)+ax^(2)+64x+(a-10).
(a) Find the value of a.
(b) Solve the equation P(x)=0.

Answer 1

Since x+2 is a factor of P(x), -2 is a zero. So P(-2) = 0. From this you can solve for a
Then you will have a third degree polynomial but you know you can divide by x+2 evenly. Do that and you have a quadratic from which you can get the remaining solutions to P(x)=0