упростите выражение:
1. (6-a) (a+2)
2. (3x-2y)(5x2-6xy+7y2)
3. (3-b)(2b+5)(b+4)

1. (6-a) (a+2)=6a+12-a²-2a=-a²+4a+122.(3x-2y)(5x2-6xy+7y2)=15x³-18x²y+21xy²-10x²y+12xy²-14y³=15x³-14y³-28x²y+33xy²3. (3-b)(2b+5)(b+4)=(3b+12-b²-4b)(2b+5)=(-b²-b+12)(2b+5)=-2b³-5b²-2b²-5b+24b+60=-2b³-7b²+19b+60