已知2y+y分之3=x 求代数式(x-y)(x-2y)-(2y-x)^2的值

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已知2y+y分之3=x求代数式(x-y)(x-2y)-(2y-x)^2的值已知2y+y分之3=x求代数式(x-y)(x-2y)-(2y-x)^2的值已知2y+y分之3=x求代数式(x-y)(x-2y)

已知2y+y分之3=x 求代数式(x-y)(x-2y)-(2y-x)^2的值
已知2y+y分之3=x 求代数式(x-y)(x-2y)-(2y-x)^2的值

已知2y+y分之3=x 求代数式(x-y)(x-2y)-(2y-x)^2的值
答:
2y+3/y=x
2y^2+3=xy
xy-2y^2=3
(x-y)(x-2y)-(2y-x)^2
=(x-y)(x-2y)-(x-2y)^2
=(x-2y)(x-y-x+2y)
=(x-2y)y
=yx-2y^2
=3

已知2y+y分之3=x 有 x-2y=y分之3
(x-y-y+y)(x-2y)-(2y-x)^2=(x-2y+y)(x-2y)-(x-2y)^2=(x-2y)^2+y(x-2y)-(x-2y)^2=y(x-2y)=y乘y分之3=3