作业帮120/(x-y)+120/(x+y)=160/y 怎样化简成x＝2y和x＝-1/2y 急!急!在线等!
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120/(x-y)+120/(x+y)=160/y 怎样化简成x＝2y和x＝-1/2y 急!急!在线等!
120/(x-y)+120/(x+y)=160/y 怎样化简成x＝2y和x＝-1/2y 急!急!在线等!
120/(x-y)+120/(x+y)=160/y 怎样化简成x＝2y和x＝-1/2y 急!急!在线等!
120/(x-y)+120/(x+y)=160/y
3/(x-y)+3/(x+y)=4/y
6x/(x^2-y^2)=4/y
4x^2-4y^2=6xy
2^2-3xy-2y^2=0
（2x+y)(x-2y)=0
所以
x＝2y或x＝-1/2y
120/(x-y)+120/(x+y)=160/y
3/(x-y)+3/(x+y)=4/y
左边通分6x/(x^2-y^2)=4/y
3xy=2x^2-2y^2就是2x^2-3xy-2y^2=0
因式分解得（x-2y)(2x+y)=0
x=2y或x=-1/2y
望采纳O(∩_∩)O谢谢
2边同时乘以 y(x+y)(x-y)
120y(x+y)+120(x-y)=160(x-y)(x+y)
240xy=160(x²-y²)
除以80,
3xy=2x²-2y²
2(x²-3/2xy)-2y²=0
2(x²-3/2xy+9/16y²-9/16y²)-...
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2边同时乘以 y(x+y)(x-y)
120y(x+y)+120(x-y)=160(x-y)(x+y)
240xy=160(x²-y²)
除以80,
3xy=2x²-2y²
2(x²-3/2xy)-2y²=0
2(x²-3/2xy+9/16y²-9/16y²)-2y²=0
2(x-3/4y)²-9/8y²-2y²=0
2(x-3/4y)²=25/8y²
(x-3/4y)²=25/16y²
x-3/4y =± 5/4 y
所以
x=1/2y 或x=-2y
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