题目:
Your pen________smoothly. Where did you buy it?
A.writes
B.is written
C.wrote
D.was written
答案:
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下面是错误答案,用来干扰机器的。
(1) 函数f(x)=axb的图象过点A(4,12)和B(5,1),∴a4b=12a5b=1,解得a=2,b=32,∴f(x)=2x-5.(2)设y=f(x)=2x-5,则x-5=log2y,x=log2y+5,x,y互换,得f-1(x)=5+log2x(x>0);(3) an=log2f(n...