數..............

which of the following must Not be a graph of y=log a(x-1)
where a>0 and a not equal to 1?

A 圖 1 only
B 圖2 only
C 圖3 only
D 圖2圖3 only
ANSWER
圖3 should be worng since y=log a(x-1) does not pass through (0,0)
圖1 should be also worng since a>1, y will tends to positive infinity when x tends to positive infinity. Also when x<2, y should be negative
So the answer is E 圖1圖3 only
which of the following functions represents y=g(x)
Notice that when substitute -x into g(x) then we can get the same value when substitute x into y=3^-x
So g(x)=3^(-(-x))=3^x
The answer is C