# Math Help - Hyperbolic Tangent

1. ## Hyperbolic Tangent

Simplify the expression tanh(lnt).
I thought the answer was (t^2-1)/(t^2+1), but that's not correct, and I can't figure out why. Can somebody give me a hand? Thanks!

2. Originally Posted by iheartthemusic29
Simplify the expression tanh(lnt).
I thought the answer was (t^2-1)/(t^2+1), but that's not correct, and I can't figure out why. Can somebody give me a hand? Thanks!
.

3. Originally Posted by iheartthemusic29
Simplify the expression tanh(lnt).
I thought the answer was (t^2-1)/(t^2+1), but that's not correct, and I can't figure out why. Can somebody give me a hand? Thanks!

Well, it is correct: $\tanh x = \frac{e^x-e^{-x}}{e^x+e^{-x}}$ , and aplying on $\ln x$ we get what you got.

Who says that's not the correct answer?

Tonio