Răspuns:
E(x) = (x-1)²-(x-2)²+(1-x)²-(2-x)²
(x-1)²=x²-2x+1
(x-2)²=x²-4x+4
(1-x)²=1²-2x+x² = 1-2x+x²
(2-x)²= 2²-4x+x² = 4-4x+x²
E(x)=(x²-2x+1)-(x²-4x+4)+(1-2x+x²)-(4-4x+x²)
E(x) = x²-2x+1-x²+4x-4+1-2x+x²-4+4x-x²
E(x)=4x+1-4+1-4
E(x)=4x-3+1-4
E(x)=4x-2-4
E(x)=4x-6 ✔