а) xy (x+y) - (x2+y2) (x-2y) Упрастите

б) (5 с-7p) (7c+5p) - (7c-5p) (5c+7p)

в) (x3+2y) (x2-2y) - (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