[(X平方+ Y平方)-(X-Y)的平方+2Y(X-Y)]÷4y的值,其中2x-y=8
问题描述：
[(X平方+ Y平方)-(X-Y)的平方+2Y(X-Y)]÷4y的值,其中2x-y=8
快 急用啊
答
答：
[(X平方+ Y平方)-(X-Y)的平方+2Y(X-Y)]÷4y
=[(x²+y²)-(x-y)²+2y(x-y)]/(4y)
=(x²+y²-x²+2xy-y²+2xy-2y²)/(4y)
=(4xy-2y²)/(4y)
=(2x-y)/2
=8/2
=4