Question

Find the zeros for this example: f(x) = x^3 + 2x^2 - 4x - 8. The answer said pos/neg 2... I don't understand how that would be the answer.. :/

Answer 1

I tried to do it by breaking it apart, and factoring two groups. And I got x^2(x+2), -4(x+2), so I don't get how he got +-2. What did I do wrong?

Answer 2

ok maybe factor it, put it in standard form then plug it into the quadratic equation and set those two equations to 0

Answer 3

I rearrange the problem like this