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DC asked in Science & MathematicsMathematics · 6 years ago

Solve for x. 3^(x-1) = 2^(x-4)?

2 Answers

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  • 6 years ago
    Favorite Answer

    3ˣˉ¹ = 2ˣˉ⁴

    Take the log base 3 of both sides:

    log₃ 3ˣˉ¹ = log₃ 2ˣˉ⁴

    Use the property of logs that says log Bˣ = xlogB:

    x-1 = (x-4)log₃ 2

    Distribute:

    x-1 = xlog₃ 2 - 4log₃ 2

    x-1 = xlog₃ 2 - log₃ 2⁴

    x-1 = xlog₃ 2 - log₃ 16

    Group x terms on L.H.S.:

    x - xlog₃ 2 = 1 - log₃ 16

    Factor out x to isolate it:

    x(1-log₃ 2) = 1 - log₃ 16

    x = (1 - log₃ 16) / (1-log₃ 2)

    If you want to get fancy, getting it down to one single logarithm, you proceed:

    x = (1 - log₃ 16) / (1-log₃ 2)

    Substitute 1 = log₃3:

    x = (log₃3 - log₃ 16) / (log₃3-log₃ 2)

    Apply property of logs that says log A - log B = log(A/B):

    x = (log₃ (3/16) / (log₃ 3/2)

    Change of base property:

    x = log{base 3/2} (3/16)

  • 6 years ago

    This link has a step by step solution to your problem:

    http://www.symbolab.com/solver/equation-calculator...

    Hope this helps

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