Can someone show me the steps to solve this problems..

Question

18s^2 + 72s = 0

and

x^3 - 5x^2 - 66x = 0

18s^2 + 72s = 0
18s*(s + 4)=0

set both terms equal to zero.

x^3 - 5x^2 - 66x = 0
x*(x^2 - 5x - 66 )= 0
factor the second term (11,6)