先化簡,再求值:
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,其中

=-2 .
.解:[(x+y)
2-y(2x+y)-8x]÷2x
=[x
2+2xy+y
2-2xy-y
2-8x]÷2x
=(x
2-8x)÷2x =

-4 把x=-2代入
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-4得
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-4 ="-1-4=-5 " 解析:
略
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科目:初中數(shù)學(xué)
來源:
題型:解答題
對于試題:“先化簡,再求值:
,其x=2”某同學(xué)寫出了如下解答:
她的解答正確嗎?如不正確,請你寫出正確解答.
解:
=
=x-3-(x+1)
=x-3+x+1
=2x-2;
當(dāng)x=2時,原式=2×2-2=2.
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科目:初中數(shù)學(xué)
來源:同步題
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有一道題:“先化簡,再求值:


,其中

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
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題型:解答題
(2006•邵陽)對于試題:“先化簡,再求值:

,其x=2”某同學(xué)寫出了如下解答:
她的解答正確嗎?如不正確,請你寫出正確解答.
解:

=

=x-3-(x+1)
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科目:初中數(shù)學(xué)
來源:2006年湖南省邵陽市中考數(shù)學(xué)試卷(課標(biāo)卷)(解析版)
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(2006•邵陽)對于試題:“先化簡,再求值:

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解:

=
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=x-3-(x+1)
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來源:湖南省中考真題
題型:解答題
對于試題:“先化簡,再求值:

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解:

=
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=x-3-(x+1)
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