5pangkatx +12/5pangkatx =7

Mapel : Matematika

Misal : [tex] 5^x = a [/tex]

[tex] 5^x + \dfrac{12}{5^x} = 7 \\ a + \dfrac {12}{a} = 7 \\ \dfrac {a^2}{a} + \dfrac{12}{a} = 7 \\ a^2 + 12 = 7a \\ a^2 - 7a + 12 = 0 \\ 5^{2x} - 7(5^x) + 12 = 0[/tex]

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