已知2x-y=10,求式子[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y_数学解答

已知2x-y=10,求式子[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y

人气：398 ℃　时间：2020-01-28 01:35:04

解答

[(x^2+y^2)-(x-y)^2+2y(x-y)]/4y
=[(x^2+y^2)-(x^2-2xy+y^2)+2xy-2y^2]/4y
=[x^2+y^2-x^2+2xy-y^2+2xy-2y^2]/4y
=(4xy-2y^2)/4y
=2y(2x-y)/4y
=(2x-y)/2
=10/2
=5