Logarithm question

[PhantomT828]

Solve for x in (5^-x) - (5^x) = 4

It appears simple but I've been unable to solve it. I've tried to take the log of 5 for both sides but I wasn't able to separate x.

 

[topsquark]

Hint: Let [imath]y = 5^x[/imath]. Then you need to solve [imath]\dfrac{1}{y} - y = 4[/imath] for y. ...........................[edited]

-Dan

 

[PhantomT828]

Hint: Let [imath]y = 5^x[/imath]. Then you need to solve [imath]\dfrac{1}{y} - y = 4[/imath] for y. ...........................[edited]

-Dan

thanks, I've got it now