Question

Calcule (x+1)²+(x-1)²+2(x+1)(x-1)

Answer 1

(x+1)²+(x-1)²+2(x+1)(x-1)=
(x+1)(x+1)+(x-1)+(x-1)+2(x+1)(x-1)=
x²+x+x+1+x²-x-x+1+2(x²-1)=
2x²+2+2x²-2=
4x²