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Math Help - System of equations

  1. #16
    is up to his old tricks again! Jhevon's Avatar
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    Here:

    -7x + \frac {27}2x + \frac 92 = -2 ...........subtract 9/2 from both sides

    \Rightarrow -7x + \frac {27}2x = - \frac {13}2 ...........combine the x's on the left

    \Rightarrow \frac {13}2x = - \frac {13}2 ............divide both sides by 13/2

    \Rightarrow \boxed{x = -1}

    now continue
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  2. #17
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    Quote Originally Posted by Jhevon View Post
    no. that's not where you went wrong. it is the line you should have checked your answer in

    you went wrong 3 lines after that. you should have subtracted 9/2 from both sides, but you did something else, i'm not even sure what
    I think I divided 9/2 from -2 instead of subtracting it
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  3. #18
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by GeinoD View Post
    Ok, how about this

    -7x+9y=-2
    -3x+2y=1

    3(-7x+9y)=-2*3
    -21x+27y=-6

    7(-3x+2y)=1*7
    -21x+14y=7

    -42x+41y=1
    i have no idea what you're doing here. stick with the method we had before. i gave you the solution for x already
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  4. #19
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    Ok, I think I understand:

    -3x+2y=1
    +3x +3x
    2y=3x+1
    /2 /2 /2
    y=3/2x+1/2

    -7x+9(3/2x+1/2)=-2

    -7x+27/2x+9/2=-2

    -7x+27/2x+9/2=-2
    -9/2 -9/2

    -7x+27/2x=-2/1-9/2

    -7x+27/2x=-4/2-9/2

    -7x+27/2x=-13/2

    13/2x=-13/2
    13/2 13/2

    x=-1

    -3(-1)+2y=1
    3+2y=1
    -3 -3
    2y=-2
    2 2
    y=-1
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  5. #20
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    And to check my answer

    -3(-1)+2(-1)=1
    3-2=1

    -7(-1)+9(-1)=-2
    7-9=-2
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  6. #21
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by GeinoD View Post
    And to check my answer

    -3(-1)+2(-1)=1
    3-2=1

    -7(-1)+9(-1)=-2
    7-9=-2
    good job. that's it!
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  7. #22
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    Oh!!! Thank you so very much, I have done 3 question now and they all check out. Thanks, I just needed to understand what I was messing up..

    Thanks
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