题目内容
(本题满分6分)先化简,再求值:
,其中
.
解:原式=
·
····················1分
=
·
························2分
=
······························4分
当
=
﹣1时,原式=
=
=
·············6分
解析:略
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题目内容
(本题满分6分)先化简,再求值:
,其中
.
解:原式=
·
····················1分
=
·
························2分
=
······························4分
当
=
﹣1时,原式=
=
=
·············6分
解析:略