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Math

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solve by graphing:
x+y=1
2x+y=0

I know that the answer is (-1,2)and i know how to mark the spot but can you explain how to draw the lines because i cant figure out the directions it goes in.

  • Math -

    To graphing a straight line:

    1. Draw your axes.

    2. Set x=0 in your equation to get the y-intercept:

    x + y = 1
    0 + y = 1
    y = 1

    so we have one point: (0,1)

    3. Set y=0 in your equation to get the x-intercept:

    x + y = 1
    x + 0 = 1
    x = 1

    so we have a second point: (1.0)

    4. Mark the two points on your graph, and use a ruler to draw the straight line that goes through them.

    I usually go for the x- and y-intercepts as my points, but any two points will do. Sometimes you can't use two intercepts, as in your second equation:

    2x + y = 0

    2(0) + y = 0

    y = 0

    So the origin (0.0) is on this line.
    The x- and y-intercepts are the same.
    We need another point. No problem; just set x = anything else, for example 3:

    2x + y = 0

    2*3 + y = 0

    y = -6

    So we can use the point (3, -6) as our second point. Mark it, and get out the ruler again to draw a straight line through (3, -6) and the origin.

    The two lines should meet at the point you expect.

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