(a-2)(a-1)-a(a+1)= (a+5)(a-2)+(a-4)(a+6)= (y-9)(3y-1)-(2y+1)(5y-7)=...

Question

(a-2)(a-1)-a(a+1)=
(a+5)(a-2)+(a-4)(a+6)=
(y-9)(3y-1)-(2y+1)(5y-7)=
(4x-1)(4x-3)-(2x-10)(8x+1)=

Answer 1

1. (а-2)(а-1)-а(а+1)=а-2•а-1+а²+1а=а*а-1а=2+1=а=3