(3x+2y)(4x-5y)-11(x+y)(x-y)+5xy,其中x=2分之七,y=-2分之5

分类: 作业答案 • 2021-12-19 10:56:11

问题描述：

答

(3x+2y)(4x-5y)-11(x+y)(x-y)+5xy
=12x²-7xy-10y²-11x²＋11y²＋5xy
=x²-2xy＋y²
=(x-y)²
=(7/2+5/2)²
=6²
=36