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Math Help - rearrange to make x the subject?

  1. #1
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    rearrange to make x the subject?

    hi,
    i need to rearrange to make x the subject, the question is below with my workings of what i think could work:

    rearrange to make x the subject?-question-plus-workings.jpg

    basically i expanded the brackets and divided by what number y was. =y and -y cancel out to leave you with 0.5x=x

    would this be correct? if not where am i going wrong? and can you help me to make this correct?

    thanks!
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  2. #2
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    The problem is that when you have been doing something to one side of the equation, you haven't done the same thing to the other side.

    You are correct up to \displaystyle 3x+6y=2x-2y.

    Now you need to collect all \displaystyle x terms on one side and all \displaystyle y terms on the other side...

    \displaystyle 3x + 6y - 2x = 2x - 2y -2x

    \displaystyle x + 6y = -2y.

    Now how would you collect all the \displaystyle y terms to the right hand side?
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  3. #3
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    so that would be x=-8y
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  4. #4
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    Correct.
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  5. #5
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    oh so now they are on their seperate sides x=-8y is the answer. i understand! thanks!!
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