А)xy(x++y2)(x-2y) б)(5с-7p)(7c+-5p)(5c+7p) в)(x3+2y)(x2-+2y)(x3-2y)

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

(5c-7p)(7c-5p)-(7c-5p)(5c+7p)=
=35c²-49pc-25pc+35p² - (35c²-25pc+49pc-35p²)=
=35c² -74pc+35p² - 35c²-24pc+35p²=
=70p² - 98pc

(x³+2y)(x²-2y)-(x²+2y)(x³-2y)=
=x⁵+2x²y-2x³y-4y²-(x⁵+2x³y-2x²y-4y²)=
=x⁵+2x²y-2x³y-4y²-x⁵-2x³y+2x²y+4y²=
=4x²y-4x³y