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Math Help - A few questions

  1. #1
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    A few questions

    I am brushing up on some math for an upcoming assessment test i have to take for post secondary. These questions are some that my teacher gave me, when i asked him what to expect for the assessment test (btw the last 2 are fractions, tried my best to make them look the part)

    1. simplify (wasnt to sure where to go with this so i did what i knew)
    = y-4[y-3(y-2)]5
    = y-4[y^2 -2y-3y+6]5
    = y-4[y^2 -5y+6]5
    = y^3(?)-5y^2.... i know im wrong here

    2.
    _1_
    1+1
    a b
    I think this is supposed to end up looking like this (im not sure of the process to get it however)
    a+b
    ab

    3.Not sure how to do this one at all
    ___a__
    a+a^2
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  2. #2
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    skeeter's Avatar
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    Quote Originally Posted by mode View Post
    I am brushing up on some math for an upcoming assessment test i have to take for post secondary. These questions are some that my teacher gave me, when i asked him what to expect for the assessment test (btw the last 2 are fractions, tried my best to make them look the part)

    1. simplify (wasnt to sure where to go with this so i did what i knew)
    = y-4[y-3(y-2)]5

    = y - 20[y-3(y-2)]

    = y - 20[y-3y+6]

    = y - 20[-2y+6]

    = y + 40y - 120

    = 41y - 120


    2.
    _1_
    1+1
    a b
    I think this is supposed to end up looking like this (im not sure of the process to get it however)
    a+b
    ab

    multiply numerator and denominator by ab ... you should get ab/(b+a)

    3.Not sure how to do this one at all
    ___a__
    a+a^2

    a/[a(1+a)] = 1/(1+a)
    ...
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  3. #3
    Senior Member eumyang's Avatar
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    Quote Originally Posted by mode View Post
    2.
    _1_
    1+1
    a b
    I think this is supposed to end up looking like this (im not sure of the process to get it however)
    a+b
    ab
    \begin{aligned}<br />
\frac{1}{\frac{1}{a} + \frac{1}{b}} &= \frac{1}{\frac{b}{ab} + \frac{a}{ab}} \\<br />
&= \frac{1}{\frac{a + b}{ab}} \\<br />
&= 1 \cdot \frac{ab}{a + b} \\<br />
&= \frac{ab}{a + b}<br />
\end{aligned}

    3.Not sure how to do this one at all
    ___a__
    a+a^2
    \begin{aligned}<br />
\frac{a}{a + a^2} &= \frac{a}{a(1 + a)} \\<br />
&= \frac{1}{a + 1}<br />
\end{aligned}

    EDIT: Too slow!
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  4. #4
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    thank you very much guys. Very helpful
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  5. #5
    MHF Contributor

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    Quote Originally Posted by mode View Post
    I am brushing up on some math for an upcoming assessment test i have to take for post secondary. These questions are some that my teacher gave me, when i asked him what to expect for the assessment test (btw the last 2 are fractions, tried my best to make them look the part)

    1. simplify (wasnt to sure where to go with this so i did what i knew)
    = y-4[y-3(y-2)]5
    skeeter is assuming this really is what you mean!

    What you do below is (y- 4)[(y- 3)(y-2)]5. Do you see the difference?

    = y-4[y^2 -2y-3y+6]5
    = y-4[y^2 -5y+6]5
    = y^3(?)-5y^2.... i know im wrong here

    2.
    _1_
    1+1
    a b
    I think this is supposed to end up looking like this (im not sure of the process to get it however)
    a+b
    ab
    \frac{1}{\frac{1}{a}+ \frac{1}{b}}
    Multiply both numerator and denominator by ab:
    \frac{ab}{ab\frac{1}{a}+ ab\frac{1}{b}}= \frac{ab}{a+ b}

    3.Not sure how to do this one at all
    ___a__
    a+a^2
    \frac{a}{a+ a^2}= \frac{a}{a(1+ a)}= \frac{1}{1+ a}
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