1) (a-4)(b+7)
2) (a-8)(-b+3)
3) (x-5)(x+7)
4) (a+3)(a^2-a-2)
5) -8(y+1)(y-5)
6) (3a+5)(3a-6)+33
7) 7x-(3x+1)(5x+1)
8) (y+3)(y+4)-y(y-1)

1)=ab+7a-4b-4×7=ab+7a-4b-28

2)=(-ab)+3a-8×(-b)-8×3=(-ab)+3a+8b-24

3)=x×x+7x-5x-5×7=x²+7x-5x-35=x²+2x-35

4)=a×(a²-a-2)+3(a²-a-2)=a³-a²-2a+3a²-3a-6=a³+2a²-5a-6

5)=(-8y-8)×(y-5)=(-8y²)-40y-8y+40=(-8y²)+32y+40

6)=9a²-18a+15a-30+33=9a²-3a+3

7)=7x-(15x²+3x+5x+1)=7x-(15x²+8x+1)=7x-15x²-8x-1=-x-15x²-1

8)=y²+4y+3y+12-y²+y=4y+3y+12+y=8y+12

Объяснение: