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Math Help - Need help making subject for equation

  1. #1
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    Need help making subject for equation

    Hey everyone,

    I am currently facing a algebra question which have stumped me for days.
    I try numerously but I was told that the way I done was wrong.
    Can you guys lend me a hand?

    I need to make
    1) �� the subject in the equation for the first question.
    2) �� the subject in the equation for the second question.

    Both of the question uses the same equation

    b = −(10��������10��+ a)

    The questions are done seperately.
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  2. #2
    Forum Admin topsquark's Avatar
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    Re: Need help making subject for equation

    Quote Originally Posted by colters View Post
    Hey everyone,

    I am currently facing a algebra question which have stumped me for days.
    I try numerously but I was told that the way I done was wrong.
    Can you guys lend me a hand?

    I need to make
    1) �� the subject in the equation for the first question.
    2) �� the subject in the equation for the second question.

    Both of the question uses the same equation

    b = −(10��������10��+ a)

    The questions are done seperately.
    You're going to have to repost this.

    -Dan
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  3. #3
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    Re: Need help making subject for equation

    Quote Originally Posted by colters View Post
    Hey everyone,

    I am currently facing a algebra question which have stumped me for days.
    I try numerously but I was told that the way I done was wrong.
    Can you guys lend me a hand?

    I need to make
    1) �� the subject in the equation for the first question.
    2) �� the subject in the equation for the second question.

    Both of the question uses the same equation

    b = −(10��������10��+ a)

    The questions are done seperately.
    b= -(10 n log_10(d)+ a)= -10 n log_10(d)- a
    Add a to both sides:
    a+ b= -10 n log_10(d)

    To solve for n, since -10log_10(d) is multiplied by it, divide both sides by those:
    -(a+ b)/(10 log_10(d))= n

    Going back to a+ b= -10 n log_10(d), to solve for d, first solve for log_10(d) by dividing both sides by -10 n to get
    -(a+ b)/(10 n)= log_10(d)

    and then "reverse" the logarithm by using its inverse function 10 to the power:
    10^(-(a+b)/(10 n))= d
    Thanks from topsquark and colters
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  4. #4
    Forum Admin topsquark's Avatar
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    Re: Need help making subject for equation

    Quote Originally Posted by HallsofIvy View Post
    b= -(10 n log_10(d)+ a)= -10 n log_10(d)- a
    Add a to both sides:
    a+ b= -10 n log_10(d)

    To solve for n, since -10log_10(d) is multiplied by it, divide both sides by those:
    -(a+ b)/(10 log_10(d))= n

    Going back to a+ b= -10 n log_10(d), to solve for d, first solve for log_10(d) by dividing both sides by -10 n to get
    -(a+ b)/(10 n)= log_10(d)

    and then "reverse" the logarithm by using its inverse function 10 to the power:
    10^(-(a+b)/(10 n))= d
    How did you get that to translate?

    -Dan
    Thanks from colters
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  5. #5
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  6. #6
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    Re: Need help making subject for equation

    Dear HallsofIvy & topsquark,

    Thank you for taking your time to answer my question.
    You all have really help me out a lot by solving my problem.

    Your Sincerely,
    Colters
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  7. #7
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    Re: Need help making subject for equation

    Quote Originally Posted by HallsofIvy View Post
    b= -(10 n log_10(d)+ a)= -10 n log_10(d)- a
    Add a to both sides:
    a+ b= -10 n log_10(d)

    To solve for n, since -10log_10(d) is multiplied by it, divide both sides by those:
    -(a+ b)/(10 log_10(d))= n

    Going back to a+ b= -10 n log_10(d), to solve for d, first solve for log_10(d) by dividing both sides by -10 n to get
    -(a+ b)/(10 n)= log_10(d)

    and then "reverse" the logarithm by using its inverse function 10 to the power:
    10^(-(a+b)/(10 n))= d

    left side should equal 10d
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