(5-a)²-(a-5)-56
=(a-5)²-(a-5)-56
a-5 7
a-5 -8
所以=(a-5+7)(a-5-8)
=(a+2)(a-13)抱歉刚刚题目打错了，
(5-a)^2-10(a-5)-56应该是27x³+8y³吧
27x³+8y³=(3x)³+(2y)³
=(3x+2y)[(3x)²-3x*2y+(2y)²]
=(3x+2y)(9x³-6xy+4y²)

原式=(a-5)²-10(a-5)-56
a-5 4
a-5-14
所以=(a-5+4)(a-5-14)
=(a-1)(a-19)麻烦这题(5-a)^2-10(a-5)-56