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Math Help - [SOLVED] 2 Substitution Problems

  1. #1
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    [SOLVED] 2 System Problems

    Hello everyone, I am doing some Algebra 2 work and I have two system equation problems that I am stuck on from a worksheet.

    "SOLVE SYSTEM EQUATION:"

    Here is the first one that I am stuck on:

    Y = 3X + 1
    Y = 3X + 5

    ------------------------------------

    Here is the second one:

    Y = 7 - 2X
    2X + Y = 7

    ------------------------------------

    Thank you in advance, I appreciate any help given.
    Last edited by WeezerGamez; August 12th 2009 at 08:13 PM.
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  2. #2
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    Quote Originally Posted by WeezerGamez View Post
    Hello everyone, I am doing some Algebra 2 work and I have two substitution problems that I am stuck on from a worksheet.

    "SOLVE EACH BY SUBSTITUTION:"

    Here is the first one that I am stuck on:

    Y = 3X + 1
    Y = 3X + 5

    3x+1 = 3x+5

    subtract 3x from both sides

    1 = 5 ... what does this tell you?



    ------------------------------------

    Here is the second one:

    Y = 7 - 2X
    2X + Y = 7

    2x + (7 - 2x) = 7

    7 = 7 ... what does this tell you?

    ------------------------------------
    ...
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  3. #3
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    Quote Originally Posted by WeezerGamez View Post
    "SOLVE EACH BY SUBSTITUTION:"

    Here is the first one that I am stuck on:

    Y = 3X + 1
    Y = 3X + 5
    Hi WeezerGamez the problem with the system of equations you have posted is that is has no solution. Therefore it can't be solved. The reason for this is each equation has a gradient of 3. This means they do not meet, they are parallel, just like train tracks.
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  4. #4
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    I thank you both for your replies... I really appreciate the help.

    If the system that I posted does not have a solution, can you explain to me what the work is that Skeeter did in the previous post? Is the work hes done so far correct? I mean, since I have to show work to show that there is no solution, I can't just write that there isn't one, is the work that was posted in the previous post sufficient enough as is to copy down? Thank you.
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  5. #5
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    Skeeter's work is sufficent to show in explaining there are no solutions.

    Skeeter's work ends with an equation that either makes no sense 1 = 5 or tells you nothing about the system 7 = 7.
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  6. #6
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    haha how can Y= 3X + 5 AND 3X + 1
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  7. #7
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    Quote Originally Posted by WeezerGamez View Post
    I thank you both for your replies... I really appreciate the help.

    If the system that I posted does not have a solution, can you explain to me what the work is that Skeeter did in the previous post? Is the work hes done so far correct? I mean, since I have to show work to show that there is no solution, I can't just write that there isn't one, is the work that was posted in the previous post sufficient enough as is to copy down? Thank you.
    A system of two linear equations may behave in any one of three possible ways:

    1. The system has infinitely many solutions.
    2. The system has a single unique solution.
    3. The system has no solution.

    the conclusion that 1 = 5 tells you there is no solution, and as stated by pickslides, the two equations represent parallel lines.

    the conclusion 7 = 7 tells you the two equations represent the same line, and that there exists an infinite number of solutions.
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