Упростите выражения:

(1-a) (2a+b) - (2+a) (1-b)

(2a-b) (a+b) - (a+2b) (a-b)

(3-m) (8+n) + (m-4) (n+6)

(9m-2n) (2m+n) - (6m+n) (3m-2n)

(1-a) (2a+b) - (2+a) (1-b) = 2a+b-2a²-ab-2+2b-a+ab=-2a²+a+3b-2

(2a-b) (a+b) - (a+2b) (a-b) = 2a²+2ab-ab-b²-a²+ab-2ab+2b²=a²+b²

(3-m) (8+n) + (m-4) (n+6) = 24+3n-8m-mn+mn+6m-4n-24=-n-2m

(9m-2n) (2m+n) - (6m+n) (3m-2n) = 18m ²+9nm-4nm-2n²-18m²+12nm-3nm+2n²=14nm