Given the function f (x) = 3x, find the value of f-1 (81).
For this case, the first thing you should do is rewrite the function.
We have then:
y = 3 ^ x
From here, we clear the value of x:
log3 (y) = log3 (3 ^ x)
log3 (y) = x
Then, we rewrite the function again:
f (x) ^ - 1 = log3 (x)
Now, we evaluate the inverse function for x = 81:
f (81) ^ - 1 = log3 (81)
f (x) ^ - 1 = 4
Answer:
the value of f-1 (81) is:
f (x) ^ - 1 = 4
To solve for x you have to bring the 12 to the other side
How do we do this?
Well if you think about it this is technically what the equation shows
This means to isolate x you can multiply both sides by 12 and that will cancel 
from the right side
can be further simplified to...
9
^^^This is the answer
Check:
3/4 = 9/12
3/4 = 3/4
Hope this helped!
~Just a girl in love with Shawn Mendes
Ok
So when you multiply by a fraction just multiply top by top and bottom by bottom
So top by top is 2 by 4 so 8
And bottom by bottom is 3 by 5 which is 15
So answer is 8/15
Hope this helps and don’t forget to mark as brainliest if you thought it was most helpful :)
