algebra homework question

Discussion in 'Teacher Time Out' started by teacherfan, Sep 14, 2011.

  1. teacherfan

    teacherfan Cohort

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    Sep 14, 2011

    It has been a while since I have had to do algebra homework but with a student in 8th grade I am learning again!

    Last night we had an argument (again!) about homework. She is graphing equations using y=mx+b. For a few of the problems she was getting a fraction for the b part and insisted that that could not be graphed. So our question is, "How do you graph a fraction?"

    Thank you!
     
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  3. bros

    bros Phenom

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    Fractions can be graphed. I know that; it works on the graphing calc. Just don't know how.
     
  4. amakaye

    amakaye Enthusiast

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    If I remember right, the 'b' is for the y-intercept, correct?

    If so, you would just graph it accordingly (as on a number line). So, 1/2 would be halfway between 0 and 1. If she's using grid paper, she could even make a scale where each square equals 1/2.
     
  5. MissCeliaB

    MissCeliaB Aficionado

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    Don't you just graph it like you would graph a whole number? Like, there's all that space between the lines on the graph paper, so that would be the fractions, right?
     
  6. teacherfan

    teacherfan Cohort

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    I thought you would just graph it like a whole number but she is not sure and doesn't want to be wrong. She is going to ask her teacher to clarify but I wanted to know as well. Thanks for the quick replies!!!!
     
  7. 3Sons

    3Sons Enthusiast

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    Depending on the fraction and the scale, you could even set the boxes differently -- so, if your fraction is one half, mark "one" after two boxes, and then your graph paper line gives you the exact halfway point. Just be sure to do the same on the x-axis.
     
  8. myangel52

    myangel52 Comrade

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    If the fraction is in the m part of y = mx +b , then treat it as rise over run. Example, if the function is y = 2/3 x + b, then go up 2, over 3 for the slope. If the fraction is in the place of the b (which, yes, is the y-intercept), find where that fraction would fall on the y-axis, graph that point, then continue on as normal for whatever the slope is.
     
  9. Aliceacc

    Aliceacc Multitudinous

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    Very often, when the y-intercept is a fraction, I tell my kids to guestimate its value. Then, as others have said, use rise/run. You'll end up getting a few other fractions, but that's OK

    Alternately, she can simply do the problem another way.

    Have her choose ANY 3 values for x, one at a time. (I usually choose 0, 1, and 2.) Plug them into the problem, and you'll get the corresponding y values. Each x and y pair combine to give you a point on the line.

    so if the equation is y = 2x - 1/2
    I get
    (0, -1/2)
    (1, 1.5)
    (2, 3.5)

    Plot the 3 points, connect them, put on your arrows and label the graph, and you're good to go.
     
  10. Blue

    Blue Aficionado

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    I am so glad I am not the parent of a school child.
     
  11. Upsadaisy

    Upsadaisy Moderator

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    Sep 15, 2011

    She could also revise the graphing paper so that every two lines equals one. Then 1/2 would be on a line. Or just use bigger graph paper so you can easily see where 1/2 would fall on the axis.
     
  12. kpa1b2

    kpa1b2 Aficionado

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    I use google to help me find those types of answers! A couple of times I've even have found the actual worksheet with answers. I have to be able to work the problem before I explain it to my son. So, I'm checking my answer, so that I can help answer his questions.
     
  13. teacherfan

    teacherfan Cohort

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    Sep 17, 2011

    Thank you to everyone for replying! I tried google for the worksheet and just a general search on y intercept but was not successful. I knew that a to z was the place to go:)! Her teacher did tell her to graph the y intercept as a fraction and estimate where it should go. I don't know what I am going to do when she gets past geometry...
     
  14. kpa1b2

    kpa1b2 Aficionado

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    Sep 17, 2011

    My son took honors geo last year. This year he'll have Alg. 2. Then I'm not for sure what. He's on track for an AP math class.

    This year he's taking Chemistry! I've never had Chem. Thankfully, right now it's stuff I learned in Bio.
     
  15. TeacherGroupie

    TeacherGroupie Moderator

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    Sep 17, 2011

  16. teacherfan

    teacherfan Cohort

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    Sep 18, 2011

    I have never heard of that website but it looks interesting. Thanks!
     

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