My Math Forum Problem with an exponential equation

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 September 7th, 2018, 11:46 AM #1 Newbie   Joined: Aug 2018 From: Czech Republic Posts: 2 Thanks: 0 Problem with an exponential equation Hi, I need help with this exponential equation. Normally, I would use 3^x as a substitution, but the 3^(-x) is kinda confusing me. How am I supposed to solve this? Thanks. 9*3^x+3^(-x)=10 So I figured it out: 1/3^x = 3^(-x) Last edited by ducanhle; September 7th, 2018 at 11:51 AM. Reason: Figured it out
 September 7th, 2018, 11:58 AM #2 Global Moderator   Joined: Dec 2006 Posts: 20,969 Thanks: 2218 If x is real, x = 0 or -2.
September 7th, 2018, 12:07 PM   #3
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Quote:
 Originally Posted by ducanhle 9*3^x+3^(-x)=10
same as: 9*3^x + 1/3^x = 10
multiply by 3^x:
9*3^(2x) + 1 = 10*3^x
continue...

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