Given the function f(x) = log3(x + 4), find the value of f−1(3).

Question

solomonzelman · Answer

You want to find,   $\large\color{black}{ \displaystyle f^{-1}\left(3\right) }$

solomonzelman · Answer

$\large\color{black}{ \displaystyle y=\log_3(x+4)}$

solomonzelman · Answer

$\bf [1]$               swipe around x and y.
$\bf [2]$               isolate the y.
$\bf [{~}lastly{~}]$     plug in 3 for x.

solomonzelman · Answer

Or, you can simply plug in 3 for y, and solve for x.

solomonzelman · Answer

$\large\color{red}{3}=\log_3(x+4)$

anonymous · Answer

so I swipe x and y in the first equation?

solomonzelman · Answer

Yes, you can swipe x and y in the first equation then solve for x, and then plug in 3 for x.

solomonzelman · Answer

Or, alternatively, you can plug in 3 for y, and solve for x.

solomonzelman · Answer

Either way you get the answer, except that way 1 is standard and way 2 is quicker.

anonymous · Answer

x=23 correct?

solomonzelman · Answer

I don't really know....

can you please tell me, how did you get this result?

anonymous · Answer

substituted 3 for y

solomonzelman · Answer

yes, and then solve for x.
23 is correct

solomonzelman · Answer

So you will get that:
$\large\color{black}{ \displaystyle f^{-1}(3)=23 }$

anonymous · Answer

Thank you for your help!!

solomonzelman · Answer

yw