If x^2=2x+2, then x^3 = ?  Choices.
A) 3x+2
B) 4x-2
C) 2x+1
D) 2x-3
E) 6x+4
x^2 = 2x+2   x^3 = x*x^2 = x*(2x+2) = 2x^2 + 2x = 2(2x+2)+2x = 6x+4   The answer is 6x+4.
<result>E</result>
If x^2=2x+2, then x^3 = ?