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Math Help - inequality

  1. #1
    ADY
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    inequality

     3 - \frac{x}{2} > 7

    is this right?

      \frac{x}{2} > 7 - 3

     \frac{x}{2} > 4

     x < 8

    ?
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  2. #2
    MHF Contributor
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    Quote Originally Posted by ADY View Post
     3 - \frac{x}{2} > 7

    is this right?

      \frac{x}{2} > 7 - 3
    No

    From  3 - \frac{x}{2} > 7

    Add \frac{x}{2} to both sides

      3 > 7 + \frac{x}{2}

    Subtract 7

      3 - 7 > \frac{x}{2}

      -4 > \frac{x}{2}

    Multiply by 2 (positive number therefore does not change the sense of the inequality)

      -8 > x
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  3. #3
    -1
    e^(i*pi)'s Avatar
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    Quote Originally Posted by ADY View Post
     3 - \frac{x}{2} > 7

    is this right?

      \frac{x}{2} > 7 - 3

     \frac{x}{2} > 4

     x < 8

    ?
    No, when multiplying or dividing by a negative number you need to change the direction of the inequality although it is usually easier to use the method running-gag used
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