(x+1)la puterea a treia = (x+1) la puterea a 2 + (x+1)
(x-2)la puterea a treia = (x-2)la puterea a 2 + ( x-2)
(x+1) la puterea a 2 = x la puterea 2 + 2x + 1
(x-2) la puterea a 2 = x la puterea 2 - 4x + 4
x la puterea 2 + 2x + 1 + x + 1 - x la puterea 2 + 4x - 4 + x - 2=8x-4 = 4 ( 2x+1)