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    Page 7 question 8 last part

    How do you remove the logbase10 from both sides?
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    You're missing an attachment. =S
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    (Original post by BananaPie)
    You're missing an attachment. =S
    http://www.ocr.org.uk/Images/59336-m...me-january.pdf
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    you just do :/ they are the same on both sides so you can just cancel?
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    Divide both sides by log10. The x^2-10/9 could be in brackets, to make it easier to see.
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    Logbase10 ((x^2-10)/x) = logbase10 (9)

    Since they're both logbase10 with no other constants or variables added to the equated equation, (x^2-10)/x has to equal 9 in order for this equated equation to work. Hence when you solve it you do not need to bother with Logbase10.

    If you're given a situation where logbase10 (2a) = logbase10 (5), then 2a = 5. However if logbase10 (2a) = logbase10 (5) + 3, then you cannot say that 2a = 5. You'll have to convert 3 into a logarithm with base 10.
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    (Original post by Acruzen)
    you just do :/ they are the same on both sides so you can just cancel?

    (Original post by Konflict)
    Divide both sides by log10. The x^2-10/9 could be in brackets, to make it easier to see.
    But log 10 / log 10 = syntax error and not 1 ?
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    (Original post by Konflict)
    Divide both sides by log10. The x^2-10/9 could be in brackets, to make it easier to see.
    Really no.

    The inverse operation of taking logs to base 10 is to exponentiate to base 10.
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    (Original post by BananaPie)
    Logbase10 ((x^2-10)/x) = logbase10 (9)

    Since they're both logbase10 with no other constants or variables added to the equated equation, (x^2-10)/x has to equal 9 in order for this equated equation to work. Hence when you solve it you do not need to bother with Logbase10.
    Yes thanks I remember my teacher telling me this
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    (Original post by IShouldBeRevising_)
    But log 10 / log 10 = syntax error and not 1 ?
    log 10 / log 10 = 1

    but that is irrelevant here as that is not the required approach.
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    (Original post by IShouldBeRevising_)
    But log 10 / log 10 = syntax error and not 1 ?
    Sorry, look at BananaPie's post!
    It uses log property: logb(b)^x=x (I think, Mr M will correct me! )
    So, log10(10^9)=x^2-10/x
    log10(10^9)=9
    9=x^2-10/x

    I don't know why I said what I said. Just ignore me.
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    (Original post by Mr M)
    log 10 / log 10 = 1

    but that is irrelevant here as that is not the required approach.
    Yes thank you, I understand now.
 
 
 
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