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Math Help - pygoream theorem 8th grade math.

  1. #1
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    pygoream theorem 8th grade math.

    ok, i dont know if im doing this right so i just need it checked by someone who is familiar with the subject.

    http://img180.imageshack.us/img180/2673/30971384nh8.jpg

    I'm not sure im doing it right, and since X=47 does that mean the red car's speed is 47miles per hr?
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  2. #2
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    Quote Originally Posted by zombie View Post
    ok, i dont know if im doing this right so i just need it checked by someone who is familiar with the subject.

    http://img180.imageshack.us/img180/2673/30971384nh8.jpg

    I'm not sure im doing it right, and since X=47 does that mean the red car's speed is 47miles per hr?
    just wanted to say in the picture i forgot to put the 5x Squared and if anyone answers my question can they teach me how to put square root symbols and stuff in forum posts.
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  3. #3
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    Bump
    Last edited by zombie; March 27th 2008 at 08:54 PM.
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  4. #4
    Behold, the power of SARDINES!
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    Quote Originally Posted by zombie View Post
    BUMP please help..
    using the theorem we get...

    (2x)^2+x^2=(105)^2 \iff 4x^2+x^2=(21 \cdot 5)^2

    5x^2=(21 \cdot 5)^2 \iff x^2=5 \cdot (21)^2

    taking the square root of both sides

    x= \pm 21\sqrt{5} \approx \pm 46.96

    We want only the positive root

    Good luck.


    as for the La tex try this link

    http://en.wikipedia.org/wiki/Help Formula
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  5. #5
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    yeap, thats what i got for the 46.96, and i rounded it off to 47. But since
    x=47 that means the red car's speed is 47 m/hr? Or do i have to times it by two since the word problem says that "the red car's speed is twice the blue car's speed" or do i divide 47 by half to get the speed of the blue car.
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  6. #6
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
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    Quote Originally Posted by zombie View Post
    yeap, thats what i got for the 46.96, and i rounded it off to 47. But since
    x=47 that means the red car's speed is 47 m/hr? Or do i have to times it by two since the word problem says that "the red car's speed is twice the blue car's speed" or do i divide 47 by half to get the speed of the blue car.
    In the original we had each velocity as x and 2x and we solved for x so the rate of the faster car will be 94
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  7. #7
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    Talking

    ok i get it now. i did everything you did except where you took (21 X 5)squared
    I just took the 105 and squared it, combined the like terms, isolated X by divining both sides by 5 and then finally took the square root of both sides to get the X squared alon and ended up with the rounded off 47. Thanks alot.
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