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i feel really stupid...log help?

so i know i should really know how to do this but for the life of me i can't remember. can someone please help me......i need to know the answer and show all my work. thanks!

find the sum: Log2 8 + log4 8 + log8 8 + log16 8 + log32 8

(the 2, 4, 8, 16, and 32 are supposed to be written slightly below the log....like the opposite way you would write an exponent.)

4 Answers

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  • 1 decade ago
    Favorite Answer

    log2 8 = 3, because 2^3 = 8

    log 4 8 = x, then 4^x = 8. 4 is 2^2, so 4^x = 2^2x = 8

    2^2x = 2^3

    2x = 3

    x = 1.5

    log8 8 = 1, since 8^1 = 8

    log16 8 = x

    16^x = 8

    2^4x = 2^3

    4x = 3

    x = 3/4

    log32 8 = x

    32^x = 8

    2^5x = 8

    5x = 8

    x = 8/5

    So we have 3 + 1.5 + 1 + 3/4 + 8/5 = 7.85

  • 1 decade ago

    convert each log to an exponent...like 2 to the x equals 8....x would equal 3 (for the first log).

    For log4 8..its 4 to the x equals 8, but make 4 = 2 raised to the second power and 8 = 2 raised to the third power...so it would be 2 raised to the 2x power equals 2 raised to the third power. then set the exponents equal to each other to get 3/2. Solve the other logs the same way

    Then add up all the answers...should be 6.85.

  • alpha
    Lv 7
    1 decade ago

    The logarithm of any real number with respect to a given base is the index of the power to which the base is to be raised to be equal to the given number.

    The given exp.=3+3/2+1+2/3+4/5=6 19/30

  • 1 decade ago

    maybe you should search websites for help because i've already forgotten Log. and i bet almost everyone else has too...

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