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電子課本網(wǎng) 第58頁(yè)

第58頁(yè)

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$? 15b c^2 ?$
$ \frac {x y}{y+x} $
D
$解:原式?=\frac {b-b-1}a?$
$? =-\frac 1a?$
解:原式?$=\frac {(a-2b)^2-(a+2b)^2}{ab}$?
?$ =\frac {-8ab}{ab}$?
?$ =-8$?
$解:原式?=\frac {a+a-b}{a+b}?$
$? =\frac {2a-b}{a+b} ?$
$解:原式?=\frac {4+x+2}{x-2}?$
$? =\frac {x+6}{x-2}?$
$解:原式?=\frac {4+2-1}{4x}?$
$? = \frac 5{4 x} ?$
$解:原式?=\frac {2(x-1)+x+5}{(x+5)(x-1)}?$
$? =\frac {3 x+3}{(x+5)(x-1)}?$
解:原式?$=\frac {x^2-y-9+y}{(x-3)^2}$?
?$=\frac {x+3}{x-3}$?
解:原式?$=\frac {a^2-(a+1)(a-1)}{a-1}$?
?$ =\frac 1{a-1} $?