x+y=3,xy=-2,求x(x+y)(x-y)-x{(x+y)的2次方} \(≥▽≤)/~

问题描述:

x+y=3,xy=-2,求x(x+y)(x-y)-x{(x+y)的2次方} \(≥▽≤)/~

原式=x(x+y)[(x-y)-(x+y)]
=x(x+y)(-2y)
=-2xy(x+y)
=-2×(-2)×3
=12