- 指数函数的解析式及定义(定义域、值域)
- 共1059题
若函数是函数
的反函数,其图象经过点
,则
______________.
正确答案
解:因为函数是函数
的反函数,则
,因为过点(4,2),因此则有a=2,故所求的为
(本题满分13分)
计算:
⑴;
(2)
正确答案
(1)
(2)
⑴解:原式=………………………………2分
= =
………………………………6分
(2)解:原式=………………………………9分
= ………………………………13分
(Ⅰ)计算:lg2+
-
÷
;
(Ⅱ)已知lga+lgb=21g(a-2b),求的值.
正确答案
解:(Ⅰ)原式=lg+
-
÷
=lg+1-lg
-
÷
=lg+1-lg
-1
=0……………………………………………………………………………………………6分
(Ⅱ)∵lga+lgb=2lg(2-2b),∴lgab=lg(a-2b)2.
∴ab=(a-2b)2,a2+4b2-5ab=0,()2-5·
+4=0.
解之得=1或
=4.……………………………………………………………10分
∵a>0,b>0,若=1,则a-2b<0,∴
=1舍去.
∴=4.…………………………………………………………………12分
略
将函数的图象先向左平移2个单位,再向下平移3个单位,得到函数的解析式为: .
正确答案
略
(本小题满分14分,每小题7分)
化简下列各式:
(1) ; (2)
.
正确答案
(1)0
(2)1
(1) 解:原式=························································ 2分
=·················································· 4分
=·········································································· 6分
=" 0···················································································" 7分
(2) 解:原式=············································ 4分
="1····································" 7分
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