Question

(x-2)^2 + x^2 - 2 . (x-1)^2

Answer 1

$(x-2)^2+x^2-2(x-1)^2=\\ \\ x^2-4x+4+x^2-2(x^2-2x+1)=\\ \\ x^2-4x+4+x^2-2x^2+4x-2=2\\ \\ a$