Identify the y-intercept. Then find use another point on the line to find the slope.
y=-1/2x+3
Practice makes perfect
Let's start by recalling the slope-intercept form of a line.
y= mx+ b
Here, m is the slope and b the y-intercept. Let's find these two values for the given line.
Finding the y-intercept
Consider the given graph.
The value of b is given by the y-coordinate of the point at which the line intercepts the y-axis. We can see in the graph that the line intercepts the y-axis at (0, 3). This means that b= 3.
y= mx+ 3
Finding the Slope
To find the slope, we will trace along the line on the given graph until we find a lattice point, which is a point that lies perfectly on the grid lines. By doing this, we will be able to identify the slope m using the rise and run of the graph.
Here we have identified (2,2) as our second point. Traveling to this point from the y-intercept requires 2 steps to the right and 1 step down.
rise/run=- 1/2 ⇔ m= -1/2
We can now write the complete equation of the line.
y= -1/2x+ 3
