а) (b-1)(b+2)-(b-2)(b+2)+(b-3)(b+2)-(b-4)(b+2=) (b+2)(b-1 -b+2 + b-3 -b+4) =(b+2) 2 =2b+4
б) (x+y)(x+1)-(x+y)(1-y)-(x+y)(x-y)=
(x+y) (x+1 - 1+y - x+y)= (x+y)2у=2ху+2у²
а) (b-1)(b+2)-(b-2)(b+2)+(b-3)(b+2)-(b-4)(b+2=)
(b+2)(b-1 -b+2 + b-3 -b+4) =
(b+2) 2 =2b+4
б) (x+y)(x+1)-(x+y)(1-y)-(x+y)(x-y)=
(x+y) (x+1 - 1+y - x+y)=
(x+y)2у=2ху+2у²