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Math... How to do this logarithms question? Question 11b please?

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  • 6 years ago
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    y log[2] 8 = x can be written as

    log[2] 8^y = x, which in the exponential notation is

    2^x = 8^y

    Hence 2^x = 64, so x = 6

    8^y = 64, hence y = 2

    log[25] (2x - 1) = y . . . → . . . 25^y = 2x - 1

    . . . . . . . . . . . . . . . . . . . → . . . (5^2)^y = 2x - 1

    But 5^y = x, so 5^2y = x^2

    therefore x^2 = 2x - 1

    x^2 - 2x + 1 = 0

    (x - 1)^2 = 0

    x = 1

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