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September 7th, 2018, 11:46 AM   #1
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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
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September 7th, 2018, 11:58 AM   #2
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If x is real, x = 0 or -2.
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September 7th, 2018, 12:07 PM   #3
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Quote:
Originally Posted by ducanhle View Post
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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