Question

y=x^4+2x^3+2x^2-4x-16 which crosses x -axis (a,0) and (0,b) where a 12 years ago

Answer 1

so b is the y intercept.. so let x = 0

then b = -16

and a is a zero of the polynomial.

Answer 2

and x = -2 is a zero of the polynomial

since P(-2) = 16 - 16 + 8 + 8 - 16

so you know that x + 2 is a factor

perhaps a little synthetic of polynomial division may help