# Hyperbolic Graph Problem

#### trojsi

Hi,
I can't understand the last step of the answer.

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#### Gusbob

Hi,
I can't understand the last step of the answer.
$$\displaystyle -2e^k + 4e^{-k} = -2$$

Moving everything to the left

$$\displaystyle -2e^k + 2 + 4e^{-k} = 0$$

Factorising $$\displaystyle -2e^{-k}$$

$$\displaystyle -2e^{-k}(e^{2k} - e^k -2) = 0$$

Divide both sides by $$\displaystyle -2e^{-k}$$

$$\displaystyle e^{2k} - e^k -2 = 0$$

trojsi

#### trojsi

tnx a lot so simple.. yet so much to assimilate

thanks again

Brandon