1)a^2-ac+a
2)3c-cm-cn
3)5x^2+5y^2x-25x
4)4y^2+4x^2y-24y
(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
<span>(9m-2n)(2m+n)-(6m+n)(3m-2n)=18m</span>²+9nm-4nm-2n²-18m²+12nm-3nm+2n²=14nm