10x^3+5x^2-20x

10x^3+5x^2-20x      if you're are tyrying to find the roots, we have

10x^3+5x^2-20x  = 0    factor

(5x) ( 2x^2 + x - 4)       x = 0   is one root

Using the quadratic formula, the other two are :   x =   [ 1 ±√33 ]  / 4