Thread: Math Question - need some help with it

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  1. #1 Math Question - need some help with it 
    Senior Member PSP Elite Hacker
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    heres the question

    Using a version of the subtraction method, find the values of x, y, and z given the following equations:
    x+y-z=6
    2y+3z=-5
    5z=-15

    Now I figgured out the equation and have it all right, but the following question asks
    How is it possible to have infanite solutions for this question. And I cant figgure out the answer to that. Any help is greatly appresheated.
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  2. #2  
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    It would be possible to have infinite solutions if you didn't know what more than one of the variables was, for example, the first part has infinite solutions, because there's no way to tell what x, y, or z is if they didn't give you the other two formulas. say I give you an equation x+y=6. There are an infinite number of solutions, because we have no idea what each variable it is. could be (3,3), could be (4,2), could be (1,5), could be (2.7, 3.3), could be any combination of numbers that comes out to 6. hope this makes sense.
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  3. #3  
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    THANK YOU. I was getting sooo confused!
    that helps alot, thanks man.
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  4. #4  
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    no prob man, looks like all those damn math classes finally came in handy, lol.
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  5. #5  
    Senior Member I Modded My PSP lead2gold's Avatar
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    Thats not true, you can solve for all the values

    the last equation first

    5z=-15
    z=-15/5
    z=-3
    Ok.. now we know Z


    2y+3z=-5 (substitute z in)
    2y+3(-3)=-5 (now we can solve for y)

    2y=(-5)-(-9)
    y=(-5)-(-9) / 2 (or)
    y=2

    Now we know y and z

    we can solve for x.

    x+y-z=6

    (substitute y and z)
    x+(2)-(-3)=6

    now we can solve for x.
    x +5 = 6
    x = 1


    Therefore, your answers are x=1, y=2, z=-3
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  6. #6  
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    but we talked about it in class and I was told that its possible for everyone to have different answers and still be right, which I dont understand how, but I guess its possible.
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  7. #7  
    Senior Member I Modded My PSP lead2gold's Avatar
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    that seems bizzare... there is only one answer to the equations above (in set)...
    Take th 5z=-15 for example... if z were anything other then (-3) that equation would be completely false.
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  8. #8  
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    He said he already solved that part. he was asking what you would have to do to make it have infinite solutions. what I was saying is if you didn't have the last equation (5z=-15), then there would be infinite solutions because there's no way you could figure out the values for the other variables. By not giving you 5z=-15, there would be infinite solutions.
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  9. #9  
    Senior Member I Modded My PSP lead2gold's Avatar
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    *slaps skull*..
    I appologize...

    i'm striking our left, right, and center on this forum.
    Sorry
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  10. #10  
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    oh don't worry, your welcome here. If you don't spam or act dumb you will probably be liked here. haha, no worries
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  11. #11  
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    you're cool dood, just don't be a douche like dende and don't spam, and you'll be fine, lol.
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  12. #12  
    Retired Moderator PSP Elite Hacker Julie's Avatar
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    yeah. we get tweaked when people make threads about questions that are either 1. stupid. 2. already been asked a million times. and 3. are easly answered by a quick google search

    its not hard to fit in here at all, just use your brain before doing anything
    R.I.P Zoidberg
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