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If we are given $x$ such that $25^x-9^y=18$ and $5^x-3^y=3$, compute $5^x+3^y$.

 Feb 19, 2021
 #1
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We can factor accordingly: \(25^x - 9^y = (5^x + 3^y)(5^x-3^y)\)

 

Therefore, \(18 = (5^x+3^y)(3)\)

 

and the answer is 6.

 Feb 19, 2021

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