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Math Help - Graphing absolute value inequalities

  1. #1
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    Graphing absolute value inequalities

    I've reached a standstill on my math homework, can someone explain how to do this? I'll post one of my questions and if possible can you show me the graph and how you would reach that point? I'd appreciate it. Also can you explain what each part of the equation means?

    f(x)=3-|x-2|

    What would it change if that 3 was a fraction such as 1/2?

    What about if there was a number after it being added? Subtracted?

    Okay that answers all my basic questions. Thanks for your help!
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  2. #2
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    See this. Can you graph 3-(x-2) and 3+(x-2)? When you want to plot functions with absolute values you should consider different cases. You should see that if x>2 then you can leave the absolute value and if x<2 then |x-2|=-(x-2). Maybe you can take a look at this as well.
    To your questions: there is no basic difference in the graphing method if you change 3 or equivalently add/subtract numbers to/from it. You can try plotting in WolframAlpha.
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  3. #3
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    Quote Originally Posted by james_bond View Post
    See this. Can you graph 3-(x-2) and 3+(x-2)? When you want to plot functions with absolute values you should consider different cases. You should see that if x>2 then you can leave the absolute value and if x<2 then |x-2|=-(x-2). Maybe you can take a look at this as well.
    To your questions: there no basic difference in the graphing method if you change 3 or equivalently add/subtract numbers to/from it. You can try plotting in WolframAlpha.
    Wolfram should be excessively helpful for the rest of this year but let me take a second to understand, you just make an input output system and using the absolute value it should eventually make a V shape... hard to describe but... I think I get it. Hm.
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  4. #4
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    Quote Originally Posted by jscalalamoboy View Post
    I've reached a standstill on my math homework, can someone explain how to do this? I'll post one of my questions and if possible can you show me the graph and how you would reach that point? I'd appreciate it. Also can you explain what each part of the equation means?

    f(x)=3-|x-2|

    What would it change if that 3 was a fraction such as 1/2?

    What about if there was a number after it being added? Subtracted?

    Okay that answers all my basic questions. Thanks for your help!
    It should be easier to plot the graph of -|x| (reflect |x| in the x axis blue line) and then move it two units to the right on the x axis (green line).

    Finally move it 3 up on the y axis (red line)
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  5. #5
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    Quote Originally Posted by e^(i*pi) View Post
    It should be easier to plot the graph of -|x| (reflect |x| in the x axis blue line) and then move it two units to the right on the x axis (green line).

    Finally move it 3 up on the y axis (red line)
    That's how the teacher explained it. I'll remember that, thanks. Haha, you're using Linux! What kind? I got UBUNTU and Grub wiped itself off my PC, so I have to use my Mac for now until I can find my Livedisk... Anyways, is there any possible way to get KM Plot on a Mac and how much does KM Plot cost?
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  6. #6
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    Quote Originally Posted by jscalalamoboy View Post
    That's how the teacher explained it. I'll remember that, thanks. Haha, you're using Linux! What kind? I got UBUNTU and Grub wiped itself off my PC, so I have to use my Mac for now until I can find my Livedisk... Anyways, is there any possible way to get KM Plot on a Mac and how much does KM Plot cost?
    I use Arch+KDEmod

    You may be able to get KmPlot as part of the KDE suite for mac but it's likely to end up being bloated and not really worth it. May be better to find the live disk first . Also KmPlot is free as in both speech and beer
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  7. #7
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    Quote Originally Posted by e^(i*pi) View Post
    I use Arch+KDEmod

    You may be able to get KmPlot as part of the KDE suite for mac but it's likely to end up being bloated and not really worth it. May be better to find the live disk first . Also KmPlot is free as in both speech and beer
    Yeah every time I boot up I get a GRUB error that says it can't find the disk.
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  8. #8
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    Quote Originally Posted by jscalalamoboy View Post
    Yeah every time I boot up I get a GRUB error that says it can't find the disk.
    Chances are you removed the partition grub part 2 was residing on. Nonetheless to avoid spamming this thread it would be better to continue via PM or VM
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  9. #9
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    Quote Originally Posted by e^(i*pi) View Post
    Chances are you removed the partition grub part 2 was residing on. Nonetheless to avoid spamming this thread it would be better to continue via PM or VM
    Okay thanks for your help anyway! I finished that part of my homework now. Test on Monday.

    "Is the ordered pair (2,-1) a solution for the inequality 5x-3y< -10?"

    I just put 2 in for x and -1 in for y, correct?
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  10. #10
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    Quote Originally Posted by jscalalamoboy View Post
    Okay thanks for your help anyway! I finished that part of my homework now. Test on Monday.

    "Is the ordered pair (2,-1) a solution for the inequality 5x-3y< -10?"

    I just put 2 in for x and -1 in for y, correct?
    Yes you do.

    I make it that the ordered pair is not a solution
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