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A melhor resposta!
2014-08-20T13:27:05-03:00
Olá Luu,

5^{2x}-2\cdot5^x+1=0.\\
(5^x)^2-2\cdot5^x+1=0.\\\\
5^x=y\\\\
y^2-2y+1=0~~(EQ.~DO~2\º~GRAU)\\\\
y'=y''=1\\\\
5^x=1\\
\not5^x=\not5^0\\\\
x=0\\\\
\Large\boxed{\boxed{S=\{0\}}}.\\.

Tenha ótimos estudos ;D
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