已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y的值

问题描述:

已知2x-y=10,求[(x²+y²)-(x-y)²+2y(x-y)]÷4y的值

答案为5
先将括号内化简 可得 2xy+2xy-2y2
再化为2y(2x-y)=20y
20y/4y=5