题目内容
先化简，再求值：
，其中
．
，其中．当
时，原式=
时，原式=解：原式=
=
=
······································································· （8分）
当时，原式=···················································· （10分）
=
=
······································································· （8分）当
时，原式=···················································· （10分）
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的结果是
元，钢笔每支y元，小明买了a支铅笔和若干支钢笔，共用去了23元，则钢笔买了___________支．
,则x的取值范围是( ).
．