先化简,再求值:(每小题6分,共12分)
(1)
,其中x = – 2;
(2)
,其中![]()
(1)-12
(2)-95
解析:
(1) 解:原式![]()
![]()
··································································· 3分
当x = – 2时,原式
··································· 4分
······························································ 6分
(2) 解:原式
····························· 2分
![]()
········································································ 4分
当
时
原式
··············································································· 6分
科目:初中数学 来源: 题型:
先化简,再求值:(每小题6分,共12分)
(1)
,其中
=-3;
(2)-x2+[3xy2-
(4x2-8xy2)+x2]-7xy2,其中x=-
,y=-2011.
查看答案和解析>>
科目:初中数学 来源:2011-2012年浙江省温岭市七年级第一学期四校期中联考数学卷 题型:解答题
先化简,再求值:(每小题6分,共12分)
(1)
,其中
=-3;
(2)-x2+[3xy2-
(4x2-8xy2)+x2]-7xy2,其中x=-
,y=-2011.
查看答案和解析>>
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