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Math Help - system of equations using substitution method

  1. #1
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    system of equations using substitution method

    How would I solve this problem using the substitution method. Any help woud be greatly appreciated. :~}

    x=y+3
    4x+y=2
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  2. #2
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    Im not sure if i did it right

    4(y+3)+y=2

    4y+12+y=2
    x=y+3
    5y+12=2 (-12 from both sides)
    5y=-10 (/ both sides by 5)
    y=-2

    Then I found x
    x=-2+3
    x=1
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  3. #3
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    Assistance

    2 Unknowns by Substitution Calculator

    Enter 4x+y=2 for Equation 1 and x-y=3 for Equation 2 and Press Calculate.

    I rearranged your Equation 1.

    Solution: (x, y) = (1, -2)

    if you want to see the opposite way of substitution method, switch equation 1 and equation 2 in the entry boxes. :-)

    Sometime later this week, I'll clean up the math portion to not show denominators of 1 and coefficients of 1. It looks like you missed a sign. Look at the section where it says:

    "Now, group like terms by getting the y variables on one side of the equation and the constants on the other side:"

    I hope this helps, let me know if you have questions.
    Last edited by mathceleb; April 22nd 2009 at 05:39 AM.
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  4. #4
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    How would i enter this into my calculator? I see an x button but no y button
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  5. #5
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    Quote Originally Posted by mathceleb View Post
    2 Unknowns by Substitution Calculator

    Enter x-y=3 for Equation 1 and 4x+y=2 and Press Calculate.

    I rearranged your Equation 1.

    (x, y) = (1, -2)

    if you want to see the opposite way of substitution method, switch equation 1 and equation 2 in the entry boxes. :-)
    I dont think it is appropriate to suggest this sort of method for what is a very easy problem.


    4(y+3)+y=2

    4y+12+y=2
    x=y+3
    5y+12=2 (-12 from both sides)
    5y=-10 (/ both sides by 5)
    y=-2

    Then I found x
    x=-2+3
    x=1
    Keep up the good work. ( and possibly change your username )
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  6. #6
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    I wish i could change my user name but i am not that good at math i do all right on the home work and stuff but when the tests come around i forget how to solve each individual problem i use one type of method on the wronge type of problem and get totaly confused lol
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  7. #7
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    Quote Originally Posted by bobak View Post
    I dont think it is appropriate to suggest this sort of method for what is a very easy problem.
    I thought it would help to show him where he missed his sign. I thought sites where you did not sell anything were acceptable. If they are not, let me know and I won't post anymore.
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  8. #8
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by mathceleb View Post
    I thought it would help to show him where he missed his sign. I thought sites where you did not sell anything were acceptable. If they are not, let me know and I won't post anymore.
    There is nothing wrong with your posting a site contains a program that will give students their answers. However the main aim of this site is to teach how to do the problems, not simply show them, and a suggestion like this will likely bend a few noses.

    -Dan
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