已知2x-y=10,求代数式{(x^2+y^2)-(x-y)^2+2y(x-y)}除4y的值.请说原因
问题描述:
已知2x-y=10,求代数式{(x^2+y^2)-(x-y)^2+2y(x-y)}除4y的值.请说原因
答
{(x^2+y^2)-(x-y)^2+2y(x-y)}除4y
=(x²+y²-x²+2xy-y²+2xy-2y²)÷4y
=(4xy-2y²)/4y
=2y(2x-y)÷4y
=(2x-y)÷2
=10÷2
=5