# Thread: Finding x of this polynomial

1. ## Finding x of this polynomial

Looking for the x of this polynomial

$\displaystyle x^3 + 3x^2 - 40 = 0$

I tried using the factor theorem but i cant find the value that makes it 0. f( ) = 0

x should = 2.66

2. It doesn't factorise, so you'll have to use a numerical method, like the bisection method or Newton's method.