x2-7x/49-x2,化简

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x2-7x/49-x2,化简
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x2-7x/49-x2,化简
x2-7x/49-x2,化简

x2-7x/49-x2,化简
(x²-7x)/(49-x²)
=x(x-7)/ [(7-x)(7+x)]
=-x /(7+x)

(x²-7x)/(7²-x²)
=[x(x-7)]/[(7-x)(7+x)]
=-x/(7+x)

x(x-7)/-(x+7)(x-7)=-x/(x+7)

是 (x^2 - 7x) / (49 - x^2) 吧?
x^2 - 7x ( 提取公因式) x(x - 7) x(x - 7) x (x - 7)
--------------- = --------------- = --------------...

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是 (x^2 - 7x) / (49 - x^2) 吧?
x^2 - 7x ( 提取公因式) x(x - 7) x(x - 7) x (x - 7)
--------------- = --------------- = ------------------ = ---------------------
49 - x^2 (49 = 7 × 7) 7^ - x^2 - (x^2 - 7^2) - (x + 7) (x - 7 )

= - x / (x + 7)

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