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 December 18th, 2018, 08:08 AM #1 Newbie   Joined: Aug 2016 From: Romania Posts: 14 Thanks: 0 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 03:20 PM.
 December 18th, 2018, 08:38 AM #2 Senior Member     Joined: Sep 2015 From: USA Posts: 2,264 Thanks: 1198 $2^x + 2^{-x} = 3$ \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*} Thanks from skeeter

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