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Math Help - Finding the equation of a straight line.

  1. #1
    NPD
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    Finding the equation of a straight line.

    I'm unsure about this question:

    <br />
y - 4 = \frac{2}{3}(x - 2)<br />



    My working:

    <br />
y - 4 = \frac{2}{3}x - \frac{4}{3}<br /> <br />

    Then adding four to both sides:

    <br />
y = \frac{2}{3}x - \frac{8}{3}<br />

    Then I multiply both sides by three to get rid of the fractions, leaving me with

    <br />
3y = 2x - 8<br />


    But according to the book, the final answer should have a positive eight rather than a negative eight. I'm not sure how to arrive at this answer (something to do with the first step in my working... is there a double negative on the right hand side?). Any help would be appreciated.
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  2. #2
    Senior Member MacstersUndead's Avatar
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    You just have a simple calculation error when you add 4 to -4/3, 4 = 12/3. 12/3 - 4/3 = 8/3
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  3. #3
    Member rtblue's Avatar
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    \displaystyle -\frac{4}{3}+4\Rightarrow -\frac{4}{3}+\frac{12}{3}=\frac{8}{3}
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  4. #4
    NPD
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    Haha, oops. Guess I was looking too hard. Thanks guys.
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