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Did i do this right? l 4-2x l > 8

  1. Mar 9, 2013 #1
    l 4-2x l >8



    4-2x>0 4-2x>8
    -2x>-4 -2x>4
    x>2 x>-2

    4-2x<0 4-2x<8
    -2x<-4 -2x<4
    X<2 X<-2




    -2< X < 2

    ANSWER- (-2,2) interval notation

    Do I have to keep doing the 4-2x>0 4-2x<0 Even tho it doesn't say it in the question?
    It is also asking me to graph it, just graph it on a number line?
     
    Last edited: Mar 9, 2013
  2. jcsd
  3. Mar 9, 2013 #2

    jbunniii

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    You can see that the answer can't be (-2,2) by taking a number in that interval such as 0 and noticing that it doesn't satisfy the inequality.

    I'm not sure why you wrote 4 - 2x > 0 and 4 - 2x < 0. These are mutually exclusive (they can't both be true), and in any case neither one of them follows from the original inequality.

    |4-2x| > 8 means precisely that 4-2x > 8 or 4-2x < -8.
     
  4. Mar 9, 2013 #3
    Kk so i don't have to do the zeros. I redid the question.

    -(4-2x)>8
    -4+2X>8
    2x>12
    X>6

    4-2x>8
    -2x>4
    x>-2

    Interval notation

    (-2,∞)
     
  5. Mar 9, 2013 #4

    jbunniii

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    OK
    No, when you divide by sides by -2 you have to reverse the inequality, so the last line should be x < -2.
     
  6. Mar 9, 2013 #5
    Are you sure that this should be in the calculus section?
     
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