# Math Help - i need some help simplifying this

1. ## i need some help simplifying this

(e^log7 - e^-log7)/(e^log7 + e^-log7)

the answer is supposed to be 24/25, but i have no idea where to begin simplifying this (find tanh (log7))

2. Originally Posted by twostep08
(e^log7 - e^-log7)/(e^log7 + e^-log7)

the answer is supposed to be 24/25, but i have no idea where to begin simplifying this (find tanh (log7))
$e^{\log{7}} = 7$

$e^{-\log{7}} = \frac{1}{7}$

$\frac{7 - \frac{1}{7}}{7 + \frac{1}{7}} = \frac{49-1}{49+1} = \frac{48}{50} = \frac{24}{25}
$

3. ooh.ok.. i dont remember that-what property of logs is that?

4. Originally Posted by twostep08
ooh.ok.. i dont remember that-what property of logs is that?
$b^{\log_b{x}} = x$

5. And that is, basically, the definition of "logarithm".