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elizabethann509 Group Title

Could someone explain to me the open and closed circles of inequalities on a number line graph and how to know if it should be open or closed and how to know what direction it should be? I know this but I always forget it! :/

  • one year ago
  • one year ago

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  1. elizabethann509 Group Title
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    I hope the question make sense!

    • one year ago
  2. zepdrix Group Title
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    |dw:1349471977348:dw|

    • one year ago
  3. Chlorophyll Group Title
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    open = excluded

    • one year ago
  4. zepdrix Group Title
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    |dw:1349472078417:dw|

    • one year ago
  5. elizabethann509 Group Title
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    open = not included closed = included Right?

    • one year ago
  6. zepdrix Group Title
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    Yah, open is the white circle c: the one that is not filled in. not included*

    • one year ago
  7. elizabethann509 Group Title
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    Buuut, what does inluded/excluded mean? lol I learned this such a long time ago and I have to do it now and I still get confused lol

    • one year ago
  8. elizabethann509 Group Title
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    Does it depend on the direction of the signs? ....... > and <

    • one year ago
  9. zepdrix Group Title
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    Well ummm, Think of like, x=2. That is a value assigned to x. we would make a black dot on the number line at 2. Inequalities are a little different. x>=2 is not a value, its an interval. x is defined not only at 2, but all values greater than 2 also. So we draw a black dot at 2, and also draw a black line in the direction for which x is defined. And then we put an arrow on the end of that line, to show that it goes on forever, ALL values greater than 2 :)

    • one year ago
  10. elizabethann509 Group Title
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    Okay :) I think i've got it :) so what would I do with something like this? -2x < 8

    • one year ago
  11. zepdrix Group Title
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    You would work with it similar to way you deal with normal equalities, try to isolate the variable term. There are some weird rules that apply to inequalities though! When you multiply or divide by a negative number, the inequality FLIPS directions! :D

    • one year ago
  12. zepdrix Group Title
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    |dw:1349472646049:dw|

    • one year ago
  13. elizabethann509 Group Title
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    haha i was just drawing that to show you. so when its like that then i divide? okay ive got it now :) thanks so much!

    • one year ago
  14. zepdrix Group Title
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    Oh sorry hehe ^^

    • one year ago
  15. elizabethann509 Group Title
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    Do these > < mean open dot and when they have lines under them does that mean the dot is closed?

    • one year ago
  16. zepdrix Group Title
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    mhm c:

    • one year ago
  17. zepdrix Group Title
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    And if you're lazy, you can type it like this <=, which is the beak with a line under it :D

    • one year ago
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