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[tex]5^{1-3x}[/tex] = 25
[tex]5^{1-3x}[/tex] = [tex]5^{2}[/tex]
1-3x = 2
-3x = 2-1
-3x = 1
-x = [tex]\frac{1}{3}[/tex]
x=[tex]\frac{-1}{3}[/tex]
2 vine de la [tex]5^{2}[/tex] care este 25
