# Equation in power

#### Petrus

##### Well-known member
Hello MHB,
I am stuck on this equation and don't know what to do, If i take ln it does not work, any advice?
$$\displaystyle 16•4^{-x}=4^x-6$$

Regards,
$$\displaystyle |\pi\rangle$$

#### Bacterius

##### Well-known member
MHB Math Helper
Try multiplying both sides by $4^x$. You get:
$$16 = (4^x)^2 - 6 \cdot 4^x$$
Now substitute $u = 4^x$. What do you see?

#### chisigma

##### Well-known member
Hello MHB,
I am stuck on this equation and don't know what to do, If i take ln it does not work, any advice?
$$\displaystyle 16•4^{-x}=4^x-6$$

Regards,
$$\displaystyle |\pi\rangle$$
Set $4^{x}=y$, then solve for y and finally find $x = \frac{\ln y}{\ln 4}$ ...

Kind regards

$\chi$ $\sigma$

#### Petrus

##### Well-known member
Hello,
Thanks for the fast respond and help from you both! i succed to solve it with correct answer!
Regards,
$$\displaystyle |\pi\rangle$$