Выполните действие
(x-5)(5-x) (8+y)(y-8)
(10-k)(k-10) (9x-5y)(9x+5y

Ответ:

1. (5x-x2-25-5x) (8y-64+y2-8y)= (-x2-25) (-64+y2)= 64x2-x2y2+1600-25y2

2. (10k-100-k2+10k) (81x2+45xy-45xy-25y2)= (-100-k2) (81x2-25y2)= - 8100x2+2500y2-81k2x2+25k2y2.