f(x)=-4x
Substitute y for f(x).
y=-4x is in the slope-intercept form of a linear equation y=mx+b, where m is the slope, and b is the y-intercept.
For y=-4x, m=-4, and b=0.
To find points on the line, substitute values for x and solve for y.
Determine the value of y if x=0.
y=-4(0)=0
So the point in which x=0 is (0,0).
To find a second point, substitute another value for x.
x=1, y=-4
So now we have two points, (0,0) and (1,-4), that we can plot and then draw a straight line through the two points.
Alternatively, you can use the slope of -4 to determine other points. You could start at the origin (0,0), and move 4 places down the y-axis, then move to the right 1 place to the point (1,-4) Conversely, you could move 4 places up the y-axis and 1 place to the left to get the point (-1,4). You can plot those points and draw a straight line through them.
graph{y=-4x [-10, 10, -5, 5]}
