I've been given the following problem to solve for x

e^2x - e^-2x = 4

which I have solved for x, by taking natural logs, to give x = 0.3466

However when I substitute the found value of x back into the equation it 
doesn't work

I just cannot understand how I can solve for x but it *doesn't* solve for 
x???

Please could someone tell me what I'm NOT doing? I'm tearing my hair out

TIA

sheri

-- 
Life may not be the party we hoped for but whilst we are here we might as 
well dance