Verified answer

1.а

(x+7)(x-2)= x²-2x+7x-14= x²+5x-14

1.б

(4c-d)(6c+3d)= 24c²+12cd-6cd-3d²= 24c²+6cd-3d²

1.в

(y+5)(y²-3y+8)= y³-3y²+8y+5y²-15y+40= y³+2y²-7y+40

2.a

y(a-b)+2(a-b)= (a-b)(y+2)

2.б

3x-3y+ax-ay= 3(x-y)+a(x-y)= (x-y)(a+3)

3.

xy(x+y)-(x²+y²)(x-2y)=x²y+xy²-(x³-2x²y+xy²-2y³)= x²y+xy²-x³+2x²y-xy²+2y³= 2y³+3x²y-x³