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evaluating logarithms...?

how to solve log5 1/25 and log27 9 without using scientific calculator...

i know these are very simple n easy...but im really confused now...

5 Answers

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  • 1 decade ago
    Favorite Answer

    Using log laws we have that log (a)b = c => a^c = b

    So, 5^x = 1/25 = 5^-2

    => x = -2

    And, 27^x = 9

    then, 3^3x = 9 = 3^2

    i.e. x = 2/3

    :)>

  • 1 decade ago

    Log5 1/25 =-2

    5^-2 = 1/25

    log is the inverse of raising a number to a power.

    Log27 9 = 2/3

    3^3 = 27, so 27^(1/3) = 3, 3^2 = 9, so [27^(1/3)]^2 = 9

    That means 27^(2/3) = 9

  • 1 decade ago

    1/25 = 5^-2 so log5 1/25 = -2

    9 = 27 ^(2/3)

    so log27 9 = 2/3

  • Anonymous
    5 years ago

    Log base 40 9 7 as an celebration is an same as 7 cases log base 40 9. Log base 25 to the ability of what's 5. The what's x. X is a variable, a range to sparkling up any equation. that is like this. Log 25 x= 25. So, what's x? X is two because 5 to the 0.33 power( 5 cases 5) is equivalent to25. Capiche? So extremely, that is 7 (log base 40 9)+ 27 (log base a million/9)/ (a million/32) (log base sixty 4)- (27/8) (log base 3/2)= the decision you are able to round it up or go away it as an same that is. it is the way you do it.

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  • 1 decade ago

    as by the logarithamic laws

    log(a base b)= p => b=a^p

    so by that

    1/25=5^x = > 5^(-2) = 5^x => x= -2

    similarly 27 = 9^x => 3^3=3^2x =>3=2x = > x = 1.5

    Source(s): my cerebrum knows logarithms in 9 th grade!!!!!!!!!!!
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