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Question:

cbrown00
cbrown00
Student
High School - 11th Grade

How do I solve x-4y=1 and 3x+4y=7 using substitution or elimination?

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Posted by cbrown00 on Thursday April 2, 2009 at 5:33 PM and tagged with equations, math.

Answers:

  1. smarthottie
    smarthottie Student
    High School - 10th Grade

    Okay, so you have the two equations:

    x-4y=1

    3x+4y=7

    Because you already have two terms that cancel out (the -4y and 4y), you will be using elimination. Simply add the two equations together.

     

    When you do this, you should get 4x=8. Divide both sides by 4 and therefore, x=2. Choose either of the equations (I would choose the x-4y=1 because the numbers are smaller), and plug in 2 for x.

    (2)-4y=1

    -4y=-1

    y=1/4

     

    So your two answers would be:

    x=2 and y=1/4

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    Posted by smarthottie on Thursday April 2, 2009 at 5:42 PM