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Math Questions. Logarithms?

1. Write Log 30 as addition of 3 Logs

2. Evaluate:

Log small 9(1/3)

****** P.S (about question 2. Can't write the small number before the base as a small number)

5 Answers

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  • 1 decade ago
    Favorite Answer

    1. Log 30 = Log (3*5*2)

    =Log 3 +Log 5+ Log2

    2. Log small 9(1/3) = [Log(1/3)]/Log9

    = (-Log 3)/ (Log 3^2)

    = (-Log3)/(2*log 3)

    =-1/2

  • 1 decade ago

    1. Write Log 30 as addition of 3 Logs

    Using the rule log(a*b*c) = log(a) + log(b) + log(c)

    you need to break 30 into any three factors such as 2*3*5=30 or 2*2*7.5 =30 and write out using the rule

    log(30) = log(2) + log(3) + log(5)

    or log(30) = log(2) + log(2) + log(7.5)

    2. Log small 9(1/3)

    I am taking this to mean evaluate log to the base 9 of 1/3

    Using the rule: log to base a of b = c as an exponential:

    is a^c = b

    Let log to the base 9 of 1/3 = m

    9^m = 1/3

    Now using logs to the base 10 take log of each side. [When using to the base 10 you can omit the small 10]

    log(9^m) = log(1/3)

    m*log(9) = log(1/3) //using ruile of logs: log(a^b) = b*log(a)

    m = log(1/3) / log(9) //divide each side by log(9)

    m= -0.4771212/0.9542425 //calculator

    m= -0.4999999 //calculator

    m= -0.5 //rounding

    Peter

  • Como
    Lv 7
    1 decade ago

    Question 1

    30 = 2 x 3 x 5

    log 30 = log (2 x 3 x 5)

    log 30 = log 2 + log 3 + log 5

    Question 2

    Let log mean log base 9

    log (1 / 3) = x

    9^x = 1 / 3

    3^(2x) = 3^(-1)

    2x = - 1

    x = - 1/2

  • holdm
    Lv 7
    1 decade ago

    log(30) = log(2*3*5) = log 2 + log 3 + log 5

    log(base 9)(1/3) = -.5 since 9^(-.5) = 1/3

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  • 1 decade ago

    1. log30=log(3*2*5)

    =log3+log2+log5

    2. (log1/3)/log9=-0.5

    log small 10 can be calculated using calculator,right?

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