Writing Slope Intercept Equations

In the equation

Let's start with finding the slope of a line on a graph. Pick a starting point (where the graph goes through the grid lines). Locate a second point and draw a triangle by going up and right or left to the next point.  Count how many you went up (rise). Count how many right (pos run) or how many left (neg run).

Find the point where the graph passes through the y-axis

The y-intercept is the y value when x=0

(0, y)

For example, if the point where it crosses the y-axis is (0, -5) we would say the y-intercept is y= -5. Since the b is the y-intercept, if we put this in the slope-intercept form it would look like y =mx + (-5) or y=mx-5.

Remember that m is the slope in the slope-intercept form

Given a slope of 3/4 and a y-intercept of 4, write the equation.
So m=3/4 and b=4 therefore
 $y\ =\ \frac{3}{4}x\ +\ 4$