
Using Slope and yIntercept to Graph Lines (page 2 of 2) Given a point on the line, you can use the slope to get to the "next" point by counting "so many up or down, and then so many over to the right". But how do you find your first point? Take a look back at the graph of the first line and its equation: y = ( ^{2}/_{3} )x – 4 crossed the yaxis at y = –4, so the equation gave us the yintercept. The second line did too: the graph of y = –2x + 3 crossed the yaxis at y = 3. This relationship always holds true: in y = mx + b, "b" gives the yintercept, and "m" is the slope. We can use this fact to easily graph straight lines:
From
the equation,
I know that the slope is m = ^{3}/_{5},
and that the line crosses the yaxis
at
As a stylistic note, you should probably pencil in the "up and over", if you are using this technique for graphing your straight line. That way, your instructor will know where your points came from. Also, if you are going to graph this way (instead of doing a Tchart of points), you will need to do your graph very neatly. If your scale on your axis is at all inconsistent or if your axes are at all crooked, this method will not work! << Previous Top  1  2  Return to Index


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