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Math Help - Linear inequalities.

  1. #1
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    Linear inequalities.

    i am trying to learn how to slove linear inequalities and im stuck!

    In problems like 6 -4x < x +1 i know the text book tells me to use -x to both sides.

    Ok.. this brings me to my question. when doing these im lost on which number to pick and subtract!! why not the 6 or the 1. please help.

    When i sit down and get ready to work the problem.. im stuck at the first step at.. do i add and sub the 6 through out the problem or or 1 or -4x.. where do i start?
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  2. #2
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    e^(i*pi)'s Avatar
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    You want to get x on only one side. By subtracting x from both sides you isolate it although I would add 4x to both sides to avoid negative inequalities giving 6 < 5x+1
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  3. #3
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    it really doesn't matter which you do first

    edit didn't see previous reply
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  4. #4
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    how would that work with this. -9<-3z-3<6 where would i start here and why? thank you for your help.. really.
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  5. #5
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    e^(i*pi)'s Avatar
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    A "compound" inequality (someone feel free to suggest a better word) is the same as -9<-3z-3 and -3z-3<6. Add 3 to both sides to get z on it's own: -6 < -3z < 9

    You can then divide by -3 but don't forget to change the direction of the inequalities
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