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Given that f(3)=5 and \(f(3x)=f(x)+2\)  for all x, find \(f^{-1}(11)\).

mathtoo  Aug 27, 2018
 #1
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The answer is 81

you can see every time we multiply x by 3, the y goes up by 2

so 11-5=6

6/2=3

3^1*3^3=3^4=81

Guest Aug 27, 2018
 #2
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(This question a little chanellge to me. Difinitely fun!)

The first anwser is right,but I think my anwser is more specific.

given f(3)=5 

f(9)=f(3)+2=5+2=7

f(27)=f(9)+2=7+2=9

f(81)=f(27)+2=9+2=11

\({f}^{-1}(11)={f}^{-1}(f(81))=81\)

Guest Aug 27, 2018

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