# Math Help - Logarithms

1. ## Logarithms

How would I find the inverse of

$
y=f(x)=4^{x}+7$
?

2. Originally Posted by juicysharpie
How would I find the inverse of

$
y=f(x)=4^{x}+7$
?
$
y = 4^x + 7
$

swap variables ...

$x = 4^y + 7$

solve for y ...

$
x - 7 = 4^y
$

$
\log_4(x-7) = \log_4(4^y)
$

$
\log_4(x-7) = y
$