Sadly is right. You must have practiced this stuff in middle school
until it was coming out of your ears. Fortunately, you have a chance
to relearn it now. You should do that ... it'll be important in any math
course you ever take.
'm' is the slope of the line on the graph.
The slope is
(the change in 'y' between any two points on the line)
divided by
(the change in 'x' between the same two points).
You can choose any two points on the line, and the slope is always the same.
To make it easy, look at the two points on this graph where the line crosses
the x-axis and the y-axis.
Going between these two points ...
-- the line goes up, from y=0 to y=4. The change in 'y' is 4 .
-- the line goes to the right, from x=-2 to x=0. The change in 'x' is 2 .
'm' = the slope = (4)/(2) = 2 .
The "y-intercept" is the place where the line crosses the y-axis.
On this graph, that's the point where y=4 .
The equation of EVERY straight line on ANY graph is:
Y = (the slope) times 'x' + (the y-intercept) .
So the equation of THIS line on THIS graph is
Y = 2x + 4 .
