Let log 2 = a, log 3 = b and log 7 = c. Express the indicated logarithm in terms of a, b, and c.

1-log3 5 (3 is the subscript of the log)

ans:(1-a)/b, i need someone to show me the step bcus my ans is different from the given ans. my ans=(1/a)-b.

1 answer

  1. remember that log3 5 = log 5/log 3

    so 1 - log3 5
    = 1 - log5/log3
    now we know 5 = 10/2
    so log 5 = log(10/2) = log10 - log2
    = 1 - log2
    = 1 - a

    so
    1 - log5/log3
    = 1 - (1-a)/b

    = (b -1+a)b

    My answer is correct, I checked and worked it out on a calculator.

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