PLEASE HELP: FAN/MEDAL?!?!
If f(x) = log3 (x + 1), what is f−1(2)?

Question

PLEASE HELP: FAN/MEDAL?!?!
If f(x) = log3 (x + 1), what is f−1(2)?

anonymous · Answer

$$f(x) = \log _{3} (x + 1)$$

anonymous · Answer

what is $$f ^{-1}(2)$$

anonymous · Answer

I don't know how to do the inverse of the log....

hartnn · Answer

here's a shortcut,
find x from 
$\Large 2= \log_3(x+1)$

anonymous · Answer

ok...
so 
$$2 \div(\log _{3}) -1$$
maybe?

hartnn · Answer

here's how that works,
$y= \log_3(x+1) \ x+1 = 3^y \ x= 3^y-1$
and so,
$f^{-1}(x) = 3^x-1$


do you know the definition of log ? 
$\Large \log_ab=c \implies b=a^c$

anonymous · Answer

ohh.... ok...
so would it be 1?

hartnn · Answer

$\Large 2= \log_3(x+1) \ \large \implies 3^2 = x+1$
you may want to try to find again from this?

hartnn · Answer

try to find "x" again ***

anonymous · Answer

so
3^2 = x + 1
3^2 = 9
9 = x + 1
8 = x?

hartnn · Answer

YES! 
thats your f^-1 (2) also :)

anonymous · Answer

Thank you so so so much! :D

hartnn · Answer

most welcome ^_^