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-   -   Substitution method (https://www.askmehelpdesk.com/showthread.php?t=78943)

  • Apr 3, 2007, 07:27 PM
    reynolds
    substitution method
    I need to solve for x and y


    x+y=4 y+-x=3
  • Apr 3, 2007, 08:57 PM
    Ionse
    you have to determine in one equation what x ( or y ) and then sub it into the other equation.

    x + y = 4 turns into x = 4 - y , then you sub that value in for x in the other equation.

    y + -(4-y) = 3 which is simplified into y -4 + y = 3 and then simplified more yet again into
    2y = 7 or y = 3 1/2

    using the value of y = 3 1/2 you can find out that x = 1/2

    very exciting imo
  • Apr 4, 2007, 08:05 AM
    cool_dude
    personally I think its faster to use elimination method in this question. Although it depends on preference. You can just add the two equations together.

    ex.
    x+y=4
    + y+-x=3
    =
    2y = 7
    y = 7/2

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