已知1/x-1/y=5,求分式3x+5xy-3y/x-3xy-y的值.已知X+1/X=3,求x平方+1/x平方的值.(两题的转化的过程?
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已知1/x-1/y=5,求分式3x+5xy-3y/x-3xy-y的值.已知X+1/X=3,求x平方+1/x平方的值.(两题的转化的过程?
1/x-1/y=5
(y-x)/xy=5
(x-y)/xy=-5
(3x+5xy-3y)/(x-3xy-y)
=[3(x-y)+5xy]/[(x-y)-3xy]
=[3(x-y)/xy+5]/[(x-y)/xy-3]
=[3×(-5)+5]/(-5-3)
=(-10)/(-8)
=5/4
x+1/x=3
(x+1/x)²=9
x²+2+1/x²=9
x²+1/x²=7
Memories_语风,你好:
(1)已知1/x-1/y=5,求分式3x+5xy-3y/x-3xy-y的值。
1/x-1/y=5
(y-x)/(xy)=5
y-x=5xy
x-y=-5xy
(3x+5xy-3y)÷(x-3xy-y)
=〔3(x-y)+5xy〕÷〔(x-y)-3xy〕
=〔3×(-5xy)+5xy〕÷〔(-5...
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Memories_语风,你好:
(1)已知1/x-1/y=5,求分式3x+5xy-3y/x-3xy-y的值。
1/x-1/y=5
(y-x)/(xy)=5
y-x=5xy
x-y=-5xy
(3x+5xy-3y)÷(x-3xy-y)
=〔3(x-y)+5xy〕÷〔(x-y)-3xy〕
=〔3×(-5xy)+5xy〕÷〔(-5xy)-3xy〕
=(-15xy+5xy)÷(-5xy-3xy)
=(-10xy)÷(-8xy)
=5/4
(2)已知X+1/X=3,求x^2+1/x^2的值。
因为(x+1/x)^2=x^2+2+1/x^2=3^3=9
所以x^2+1/x^2=9-2=7
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