The slopeintercept form for the equation of a straight line is:
y = mx + b
where m is the slope and b is the yintercept.
1. y = 4x  3 = 4x + (3). 3 is the yintercept
2. y = mx + b. m is the slope, and b is the yintercept,
3. The slope (m) of the line is the change in y over the change in x between any two points on the line. We have two points in ordered pair format (x,y): (2,8) and (0.4)
Change in y = 4  (8) = 4 + 8 = 4
Change in x = 0  2 = 2
m = Change in y/Change in x = 4/(2) =
2
So far:
y = 2x + b
To find b, plug one of the (x,y) points into the equation, say point M, (2,8):
y = 2x + b
8 = 2(2) + b [Plug in y=8, x=2]
8 = 4 + b
4 = b (the yintercept)
The equation of the line is:
y = 2x 4
8/1/2014

Philip P.