已知 2x-y=10,求【（x^2+y^2(-(x-y)^2+2y(x-y)】除以y的值_数学解答

已知 2x-y=10,求【（x^2+y^2(-(x-y)^2+2y(x-y)】除以y的值

人气：446 ℃　时间：2020-04-28 11:43:10

解答

[(x^2+y^2)-(x-y)^2+2y(x-y)]/y
=[(x^2+y^2)-(x^2-2xy+y^2)+2xy-2y^2]/y
=[x^2+y^2-x^2+2xy-y^2+2xy-2y^2]/y
=(4xy-2y^2)/y
=2y(2x-y)/y
=2(2x-y)
=2×10
=20