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    work out the value of x when

    2^30/8^9=2^x

    how would i do this
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    Replace 8 with 2^3.
  3. Offline

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    (Original post by little_wizard123)
    Replace 8 with 2^3.
    ok so 2^30/2^3=2^x
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    (Original post by zed963)
    work out the value of x when

    2^30/8^9=2^x

    how would i do this
     \displaystyle \frac{2^{30}}{8^9} = 2^x

    Remember,  8 = 2^3 , hence,  8^9 can be written as  (2^3)^9
    Now use the law,  (a^x)^b=a^{xb}
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    (Original post by zed963)
    ok so 2^30/2^3=2^x
    No. You have replaced 8^9 by 2^3.

    8^9 = (2^3)^9. Then simplify this with an indices rule.
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    (Original post by raheem94)
     \displaystyle \frac{2^{30}}{8^9} = 2^x

    Remember,  8 = 2^3 , hence,  8^9 can be written as  (2^3)^9
    Now use the law,  (a^x)^b=a^{xb}
    so 2^30-2^27=2^3
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    (Original post by zed963)
    so 2^30-2^27=2^3
    Is the '-' a typo?
    It should be a divisor.

    Yes, we get  2^3 , but what is the value of  x \ ?
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    (Original post by raheem94)
    Is the '-' a typo?
    It should be a divisor.

    Yes, we get  2^3 , but what is the value of  x \ ?
    Yeah it's a typo

    x=3
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    2^30 / 8^9 = 2^x
    2^30 / (2^3)^9 = 2^x
    2^30 / 2^27 = 2^x
    2^3 = 2^x

    x = 3
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    (Original post by zed963)
    Yeah it's a typo

    x=3
    :yep:

    You are getting better at maths!
  11. Offline

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    (Original post by kuroudo93)
    2^30 / 8^9 = 2^x
    2^30 / (2^3)^9 = 2^x
    2^30 / 2^27 = 2^x
    2^3 = 2^x

    x = 3
    You may like to have a look at the forum rules, full solutions are considered a last resort.

    So always first give hints, please don't post full solutions.
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    just expand 2^30 and divide it by 8^9 and you'll get 8. therefore x is 3
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    (Original post by lmartynofficial)
    just expand 2^30 and divide it by 8^9 and you'll get 8. therefore x is 3
    Can you please clarify what do you mean by expand 2^30?
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    (Original post by lmartynofficial)
    just expand 2^30 and divide it by 8^9 and you'll get 8. therefore x is 3
    You make it sound easy.
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    (Original post by raheem94)
    Can you please clarify what do you mean by expand 2^30?
    I think he literally means do 2*2*2*2.... 30 times and write the value without indices. And then the same with 8^9
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    (Original post by hassi94)
    I think he literally means do 2*2*2*2.... 30 times
    My also guess was that he means this, but it doesn't looks sensible.

    How will he divide by 8^9, any idea?
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    (Original post by raheem94)
    My also guess was that he means this, but it doesn't looks sensible.

    How will he divide by 8^9, any idea?
    It is a pretty terrible solution to the problem.

    Well you get 1073741824/134217728 and then he somehow sees that that = 8.

    It's a silly solution, I wouldn't worry
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    (Original post by hassi94)
    It is a pretty terrible solution to the problem.

    Well you get 1073741824/134217728 and then he somehow sees that that = 8.

    It's a silly solution, I wouldn't worry
    That solution does actually work.
  19. Offline

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    (Original post by hassi94)
    It is a pretty terrible solution to the problem.

    Well you get 1073741824/134217728 and then he somehow sees that that = 8.

    It's a silly solution, I wouldn't worry
    At least he isn't trying to use the infinity concept someone used yesterday. lol

    OP, please ignore post#12.
  20. Offline

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    (Original post by zed963)
    That solution does actually work.
    We know it works, but how will you do it without a calculator?
    You won't be able to see that the value is 8 without a calc.

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