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Maths- solve 4^x=9 giving your answer to 3dp Watch

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    solve 4^x=9 giving your answer to 3dp (3 marks)
    is this to do with logs? how do i do it
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    (Original post by dongonaeatu)
    solve 4^x=9 giving your answer to 3dp (3 marks)
    is this to do with logs? how do i do it
    log49 = ?

    Just remember 23=8
    and log28 = 3
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    It is indeed. Take logs of both sides

    so xlog4=log9
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    (Original post by dongonaeatu)
    solve 4^x=9 giving your answer to 3dp (3 marks)
    is this to do with logs? how do i do it
    Start with taking logs of both sides and then see if you can rearrange to get x=
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    yes it is

    take logs of both sides

    use the rule log(ab) = blog(a)
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    (Original post by TenOfThem)
    yes it is

    take logs of both sides

    use the rule log(ab) = blog(a)
    i get 1.584962501

    to 3dp is it: 1.585
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    (Original post by J10)
    It is indeed. Take logs of both sides

    so xlog4=log9
    1.585 is that the answer for x
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    (Original post by dongonaeatu)
    1.585 is that the answer for x
    Yep

    Also without a calculator you know 4^1 = 4 and 4^2 = 16 so x is going to be between 1 and 2 so 1.585 sounds sensible. A useful check if you don't have a calculator
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    (Original post by TenOfThem)
    yes it is

    take logs of both sides

    use the rule log(ab) = blog(a)
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    (Original post by TheGrinningSkull)
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    hey man is turning point the same as stationary point?
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    (Original post by dongonaeatu)
    hey man is turning point the same as stationary point?
    For the most part, yes
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    You should really pay more attention in class.
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    (Original post by Lilium)
    You should really pay more attention in class.
    LoL

    I expect that to become your sig ...
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    (Original post by dongonaeatu)
    hey man is turning point the same as stationary point?
    Like TenOfThem said, for the most part yes, turning points are when you have minimums and maximums where the gradient changes at the stationary point, however this isn't always the case such as points of inflection.
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    (Original post by nm786)
    log4^x=log9

xlog4=log9

therefore log9/log4=x

x=1.58
    You're a bit late to the party. Also, 3dp.
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    (Original post by Contrad!ction.)
    You're a bit late to the party. Also, 3dp.
    yeah.
    i thought it said 3sf
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    (Original post by nm786)
    yeah.
    i thought it said 3sf
    even if it was 3 significant figures wouldn't it be 1.59 instead of 1.58
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    (Original post by nm786)
    yeah.
    i thought it said 3sf
    Haha sneaky edit. I'm a chronic misreader so I suppose I can't really talk

    Like in C2 where I ended up losing out on full UMS because of it :ninja:
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    (Original post by zed963)
    even if it was 3 significant figures wouldn't it be 1.59 instead of 1.58
    no it would be 1.58 as there is a 4 after it and 4 is less than 5,
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    (Original post by zed963)
    even if it was 3 significant figures wouldn't it be 1.59 instead of 1.58
    Nope, it's 1.58496...... so 3sf = 1.58 and 3dp = 1.585.

    When I saw that, I checked
 
 
 
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