已知2x=5y,求分式x-y/x+y的值

已知2x=5y,求分式x-y/x+y的值


我服了.你把x=2.5y代進去算不就出來了



使分子,分母各項係數的絕對值是最小整數,則分式(0.02x+0.06y)/(0.8x-0.2y)


(0.02x+0.06y)/(0.8x-0.2y)
=(2x+6y)/(80x-20y)
=(x+3y)/(40x-10y)



不改變分式的值,把下列分式的分子分母中各項係數化為整數1.0.2x+y/0.1x-0.3y
2.0.5x+0.25y/0.5x-1/3y


1.0.2x+y/0.1x-0.3y
=(1/5x+y)/(1/10x-3/10y)
=[(x+5y)*1/5]/[(x-3y)*1/10]
=2(x+5y)/(x-3y)
2.0.5x+0.25y/0.5x-1/3y
=(1/2x+1/4y)/(1/2x-1/3y)
=[(2x+y)*1/4]/[(3x-2y)*1/6]
=3(2x+y)/2(3x-2y)