题目内容
若
，且
．
（1）求
的最小值及对应的x值；
（2）若不等式
的解集记为A，不等式
的解集记为B，求
．
，且．（1）求
的最小值及对应的x值；（2）若不等式
的解集记为A，不等式的解集记为B，求．20．(1) ∵
∴
，∴
∴a = 2或a = 1（舍）····································································· 2分
又∵
∴
∴
b
=" 2······························································" 4分
∴
，
∴当
时，的最小值为
······························· 6分
(2) 由
∴
∴
∴
，即
······································· 9分
由
∴
∴
······································································· 11分
∴
···································································· 12分
∴
，∴∴a = 2或a = 1（舍）····································································· 2分
又∵
∴
∴b=" 2······························································" 4分∴
，∴当
时，的最小值为······························· 6分(2) 由
∴
∴
∴
，即······································· 9分由
∴
∴
······································································· 11分∴
···································································· 12分略
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