That is, x 3+3x2+3x2 = 0.
Because (x+1) 3 = x3+3x2+x+3x+1.
So x3+3x2+3x2 = (x+1) 3+1= 0.
That is, (x+ 1) 3 =- 1.
So X+ 1=- 1.
The solution is X=-2.