posted by ted on .
How do you factor X^3+5x^2-28x-32?
let f(x) = x^3 + 5x^2 - 28x - 32
I tried x = ±1, ±2, ±4 (that is, factors of 32)
on the second try, I found f(-1) = 0
so x+1) is a factor
Using synthetic division I found
x^3 + 5x^2 - 28x - 32 = (x+1)(x^2 + 4x -32) which factored again to