先化簡,再求值:
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,其中x=2.
【答案】
分析:先把括號內(nèi)通分得到原式=
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•

,然后進行約分得到原式=

,再把x=2代入計算即可.
解答:解:原式=[
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-
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]•

=
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•
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=
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,
當x=2時,原式=

=
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.
點評:本題考查了分式的化簡求值:先通過通分計算括號內(nèi)的分式加減,再把各分子和分母因式分解,然后進行約分得到最簡分式,最后把滿足條件的字母的值代入計算得到原分式的值.
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