Precalculus

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1.Solve 5^(2x) -4(5^x)=12

2. Solve Log[8](log[8]x)=0

  • Precalculus -

    let 5^x = y , then we have

    y^2 - 4y - 12 = 0
    (y-6)(x+2) = 0
    y = 6 or y = -2

    5^x = 6
    xlog5 = log6
    x = log6/log5 = appr. 1.1133
    or
    5^x = -2
    xlog5 = log (-2), but we cannot take logs of negatives, so no solution for that case

    x = log6/log5 or 1.1133

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