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Thread: graphing equations

  1. #1

    graphing equations

    how do u graph a equation that has decimal?
    7.1x -3.9y=1.4
    how do i graph this?
    i dont know how to get started.

  2. #2
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    Re: graphing equations

    Multiply both sides by 10 and go from there.

  3. #3
    Elite Member mmm4444bot's Avatar
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    Determine the two intercepts; plot them, and use a straightedge to draw a line through them.

    The x-intercept is on the x-axis, so the y-coordinate must be zero because we don't go up or down.

    (x, 0)

    Substitute 0 into the equation for y, and solve for x.

    The y-intercept is on the y-axis, so the x-coordinate must be zero because we don't go left or right.

    (0, y)

    Substitute 0 into the equation for x, and solve for y.

    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  4. #4

    Re: graphing equations

    where did u get the 10 from?

  5. #5

    Re: graphing equations

    after i am done with this process do can i get the slope and the x- intercept?
    after i substitude the 0 for y i got this...
    7.1x-3.9y=1.4
    7.1x-3.9(0)=1.4
    7.1x=1.4
    7.1x/7.1=1.4/7.1
    x=197.18 is this correct?

  6. #6
    Elite Member mmm4444bot's Avatar
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    Did they ask you to do anything other than graph the equation ? I mean, are you free to graph it using any method?

    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  7. #7
    Elite Member mmm4444bot's Avatar
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    Quote Originally Posted by Irma Garcia

    7.1x/7.1=1.4/7.1

    x=197.18 is this correct? No
    Are you using a calculator to divide 1.4 by 7.1 ?

    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  8. #8
    Elite Member mmm4444bot's Avatar
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    Here is a set of axes for you to use, when you get the coordinates of two points to plot.

    The axes go from x = -1 to 1 horizontally and y = -2 to 1.5 vertically.

    [attachment=0:35wun6d9]xy-plane.JPG[/attachment:35wun6d9]

    Attached Images Attached Images
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  9. #9
    Elite Member mmm4444bot's Avatar
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    Since both intercepts are close to the Origin, let's plot four points, instead of two. It's easy.

    In addition to the two intercepts, also find the following.

    (-1, y)

    (1, y)

    In other words, find y when x = -1 and also when x = 1.

    Plotting four points will make it easier to draw a fairly accurate line segment.

    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  10. #10
    Elite Member mmm4444bot's Avatar
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    Your work is okay, but you made an arithmetic mistake at the end.

    x = 1.4/1.7

    x = 0.197

    I think we can round that off to 0.2, for graphing purposes.

    The x-intercept is (0.2, 0).

    What do you get for the y-intercept (0, y) ?

    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

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