求两道数学题的解法、过程与答案!非常急!在线等!!!
(1)已知1/X-1/Y=3,求分式(2X+3XY-2Y)/(X-2XY-Y)的值。(2)化简:(x的二次方-2xy+y的二次方-1)/(x-y-1)=...
(1)已知1/X-1/Y=3,求分式(2X+3XY-2Y)/(X-2XY-Y)的值。
(2)化简:(x的二次方-2xy+y的二次方-1)/(x-y-1)= 展开
(2)化简:(x的二次方-2xy+y的二次方-1)/(x-y-1)= 展开
3个回答
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(1)∵1/X-1/Y=3∴y-x=3xy
分式(2X+3XY-2Y)/(好慧X-2XY-Y)=[-2﹙y-x﹚+3XY]/[-﹙y-x﹚-2XY]
=﹙-6XY+3XY﹚/友消答﹙-3xy-2xy﹚
=﹙-3xy﹚/﹙-5xy﹚
=3/5
(2):(x的二次方-2xy+y的二次方-1)/(x-y-1)=﹙x²桥拦-2xy+y²-1﹚/﹙x-y-1﹚
=[﹙x-y﹚²-1]/﹙x-y-1﹚
=[﹙x-y+1﹚﹙x-y-1﹚]/﹙x-y-1﹚
=x-y+1
分式(2X+3XY-2Y)/(好慧X-2XY-Y)=[-2﹙y-x﹚+3XY]/[-﹙y-x﹚-2XY]
=﹙-6XY+3XY﹚/友消答﹙-3xy-2xy﹚
=﹙-3xy﹚/﹙-5xy﹚
=3/5
(2):(x的二次方-2xy+y的二次方-1)/(x-y-1)=﹙x²桥拦-2xy+y²-1﹚/﹙x-y-1﹚
=[﹙x-y﹚²-1]/﹙x-y-1﹚
=[﹙x-y+1﹚﹙x-y-1﹚]/﹙x-y-1﹚
=x-y+1
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1、1/X-1/Y=3 可得 x-y=-3xy
(2X+3XY-2Y)/闹纯肆(X-2XY-Y)裤隐=(3xy-6xy)/(-3xy-2xy)=3/5
2、(x^2-2xy+y^2-1)/液轿(x-y-1)=[(x-y)^2-1]/(x-y-1)
=(x-y+1)(x-y-1)/(x-y-1)
=x-y+1
(2X+3XY-2Y)/闹纯肆(X-2XY-Y)裤隐=(3xy-6xy)/(-3xy-2xy)=3/5
2、(x^2-2xy+y^2-1)/液轿(x-y-1)=[(x-y)^2-1]/(x-y-1)
=(x-y+1)(x-y-1)/(x-y-1)
=x-y+1
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那么简单 别拿出来卡 变形 就可以
了
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