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Math Help - How do you do system of equations?

  1. #1
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    How do you do system of equations?

    Ok, i was just on a site for tutoring but it isn't making much sense to me!
    What steps do i follow through when doing this?

    y=3x+7
    y=x-9
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  2. #2
    Senior Member topher0805's Avatar
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    To solve it, set the two expressions equal to each other.

    3x+7 = x-9

    Then solve for x, to get:

    x=-8
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  3. #3
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    ok, so on one like

    y=2x+3
    y=3x+1

    itll be 2x + 3=3x+1?

    and solve from there? aren't you suppose to change signs when bringing it over?
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  4. #4
    Senior Member topher0805's Avatar
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    Switch signs? Sort of, let me give you a step by step version of this:

    2x+3=3x+1

    Subtract 1 from both sides:

    2x+2=3x

    Subtract 2x from both sides:

    <br />
2=1x

    So:

    x=2

    Do you see?
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  5. #5
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    I think so.

    So on one like

    y=2x-10
    y=4x-8

    itll be 2x-10 = 4x-8

    2x=-2

    x=-1?

    ha i suck at combining like terms and what not lol.
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  6. #6
    Senior Member topher0805's Avatar
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    Yeah, it looks like you've got it now.
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  7. #7
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    Yay! Thanks for your time! = ]
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  8. #8
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by topaz192 View Post
    Ok, i was just on a site for tutoring but it isn't making much sense to me!
    What steps do i follow through when doing this?

    y=3x+7
    y=x-9
    Please do not double post.

    User warned.

    -Dan
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