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December 18th, 2018, 07:08 AM   #1
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Exponential equation problem

I have the following equation
2^x+2^(-x)=3
4^x+4^(-x)=?
The solution is 7, but I don't know how to reach that answer. Can anyone help me?

Last edited by skipjack; December 18th, 2018 at 02:20 PM.
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December 18th, 2018, 07:38 AM   #2
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$2^x + 2^{-x} = 3$

$\begin{align*}

&9 = \\

&(2^x+2^{-x})^2 = \\

&2^{2x}+2+2^{-2x} = \\

&4^x + 2 + 4^{-x}\\

&4^x + 4^{-x} = 7

\end{align*}$
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