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Thread: Help needed.

  1. #1
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    Help needed.

    Please help me to solve these four:

    X^2 = 9/16

    and

    X/6 = 15 + x

    and

    X^2 - X - 6 = 0

    and

    2x^2 - 3x = 0


    Thank you very much!
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  2. #2
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    Quote Originally Posted by Shandy View Post
    Please help me to solve these four:
    Thank you very much!
    X^2 = 9/16
    $\displaystyle (\sqrt{x})^2=\sqrt{\frac{9}{16}}$

    $\displaystyle x=\frac{3}{4}$
    $\displaystyle x= -\frac{3}{4}$ as corrected by earboth

    $\displaystyle X/6 = 15 + x$
    $\displaystyle \frac{x}{6}*\frac{6}{6}= 6(15 + x)$

    $\displaystyle x= 90 +6x$

    $\displaystyle x-6x = 90$

    $\displaystyle -5x = 90$

    $\displaystyle x= -18$

    X^2 - X - 6 = 0
    $\displaystyle (x+2)(x-3)=0$

    $\displaystyle x+2=0 | x-3=0$

    $\displaystyle x=-2 |x=3$


    2x^2 - 3x = 0

    try doing the last one.
    Last edited by princess_21; Feb 3rd 2009 at 01:46 AM.
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  3. #3
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    Quote Originally Posted by Shandy View Post
    Please help me to solve these four:

    X^2 = 9/16

    ...
    Keep in mind that $\displaystyle \sqrt{x^2} = |x|$

    Calculate the square root on both sides of your equation:

    $\displaystyle x^2=\dfrac9{16}~\implies~|x|=\dfrac34~\implies~x=-\dfrac34~\vee~x=\dfrac34$
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  4. #4
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    forgot that part. thanks
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