Graphs Using Slope-Intercept Form

Key Questions

  • How do you know if you graphed the linear equation correctly?

    If your line goes through two distinct points of the equation, then your line is correct.

    I hope that this was helpful.

    Wataru · 1 · Nov 9 2014
  • Once you graph the y-intercept, how do you determine the second point?

    You can choose any nonzero value x_2 for x and plug it into the equation of the line you are working on to find the corresponding y-coordinate y_2. Your second point is (x_2,y_2).

    I hope that this was helpful.

    Wataru · 1 · Nov 1 2014
  • How do you graph a line using slope-intercept form?

    The equation of a line in explicit form is:

    y=mx+q, where m is the slope and q the y-intercept.

    It is easier to show the procedure with some example:

    y=2: this line is parallel to the x-axis and it passes from the point P(0,2).

    x=3: this line is parallel to the y-axis and it passes from the point P(2,0).

    y=x+1: this line is parallel to the bisector of the I and III quadrants and it passes from the point P(0,1).

    graph{x+1 [-10, 10, -5, 5]}

    y=-x-1: this line is parallel to the bisector of the II and IV quadrants and it passes from the point P(0,-1).

    graph{-x-1 [-10, 10, -5, 5]}

    y=2/3x+1: we have to find the point P(0,1), from this point we have to "count" 3 units to the right and then 2 units to the up, so we can find the point #Q(3,3), then we have to join the two point found.

    graph{2/3x+1 [-10, 10, -5, 5]}

    y=-1/2x-1: we have to find the point P(0,-1), from this point we have to "count" 2 units to the left and then 2 units to the up, so we can find the point #Q(-2,0), then we have to join the two point found.

    graph{-1/2x-1 [-10, 10, -5, 5]}

    The difference in these two last examples is the "choice" of the "right" and the "left". Right, if the m is positive; left, if the m is negative.

    Massimiliano · 1 · Jan 30 2015

Questions

Graphs of Linear Equations and Functions