已知x+y=5 xy=6 求x(x+y)(x-y)-x(x+y)눀

2025-01-21 08:48:03
推荐回答(1个)
回答1:

x(x+y)(x-y)-x(x+y)²
=x(x+y)[(x-y)-(x+y)]
=x(x+y)(x-y-x-y)
=-2xy(x+y)
因:x+y=5,xy=6
所以原式=-2X6X5=-60