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Math Help - Several simple exponent problems, Please help.

  1. #1
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    Several simple exponent problems, Please help.

    Hi, I am new to the forum. I have been stuck on a few math problems involving exponents for a while now and i don't know where else to turn.

    I have attached a pdf file with my work and the questions i need help with are as follows. * These are not going to be marked and we were given most of the answers, so please explain to me and don't just give me the answer

    as you can see all the answers are already given so i'm not trying to cheat.. or be lazy and get people to work for me.. I benefit in no way whatsoever.

    section a


    2.a) Okay the answer for this one is supposed to be 3 √1/32
    But i don't understand how to arrive at this. I really don't even know where to start because i don't understand my teacher (currently working on switching teachers)

    2.b) same as 2.a idk..

    The rest i get

    Then to section B
    9.) i)
    ii)


    Please explain these. There are more i don't understand but i'm hoping by you explaining these to me i will be able to complete the rest.
    Attached Files Attached Files
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  2. #2
    MHF Contributor Siron's Avatar
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    Re: Several simple exponent problems, Please help.

    Let's start with exercice 2.
    2.a Multiply each side with x^{\frac{1}{2}}
    2.b
    x^{\frac{1}{2}} +\frac{1}{2}x^{\frac{-1}{2}}(x-9)=0
    \Leftrightarrow x^{\frac{1}{2}}+\frac{1}{2}x^{\frac{-1}{2}}x - \frac{9}{2}x^{\frac{-1}{2}}=0
    \Leftrightarrow x^{\frac{1}{2}}+\frac{1}{2}x^{\frac{1}{2}}-\frac{9}{2}x^{\frac{-1}{2}}=0
    Same here, mulitply each side with x^{\frac{1}{2}}.
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  3. #3
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    Re: Several simple exponent problems, Please help.

    \displaystyle x^{\frac{-3}{2}}-\frac{1}{9}x^{\frac{-1}{2}} = 0

    Make \displaystyle x^{\frac{-1}{2}} = u then you have

    \displaystyle u^3-\frac{1}{9}u = 0 solve this cubic by factoring out  u then applying the difference of two squares.

    You should get \displaystyle  u = 0, \frac{-1}{3}, \frac{1}{3}  \implies  x = \frac{1}{\sqrt{0}}, \frac{1}{\sqrt{\frac{-1}{3}}}, \frac{1}{\sqrt{\frac{1}{3}}} <br />

    Throw out the first two answers for reasons linked with the domain of the real numbers.
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  4. #4
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    Re: Several simple exponent problems, Please help.

    2. (a) I do not agree with your given solution. The expression will factor ...

    x^{-3/2} \left(1 - \frac{x}{9}\right) = 0

    x = 9 is the only solution.


    2. (b) this expression will also factor ...

    x^{-1/2} \left(x + \frac{x-9}{2} \right) = 0

    x = 3 is the only solution



    problem 9 follows the same procedure as problem 2 ...

    9. (i) factor out x^{-1/3}

    (ii) factor out x(x+5)^{-1/2}
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  5. #5
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    Re: Several simple exponent problems, Please help.

    For 2a the exponents are positive not negative as i view them with a magnifying glassand my answer is 1/9
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  6. #6
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    Re: Several simple exponent problems, Please help.

    Quote Originally Posted by bjhopper View Post
    For 2a the exponents are positive not negative as i view them with a magnifying glassand my answer is 1/9
    attached is a snapshot I copied ...
    Attached Thumbnails Attached Thumbnails Several simple exponent problems, Please help.-expprob.png  
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  7. #7
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    Re: Several simple exponent problems, Please help.

    Thanks very much everybody. And sorry for the late reply.
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