Explicație pas cu pas:
E(x)=(x²+x-1)²-(x²-2)²-2x(x+1)(x-1)+3
Folosim a²-b²=(a+b)(a-b) pentru primii 2 termeni
E(x)=(x²+x-1+x²-2)(x²+x-1-x²+2)-2x(x+1)(x-1)+3 =>
E(x)=(2x²+x-3)(x+1)-2x(x+1)(x-1)+3=>
E(x)=(x+1)*[2x²+x-3-2x(x-1)]+3=>
E(x)=(x+1)(2x²+x-3-2x²+2x)+3=>
E(x)=(x+1)(3x-3)+3=>E(x)=3(x+1)(x-1)+3=>
E(x)=3(x²-1)+3=>E(x)=3x²-3+3=>E(x)=3x²
