Identify the y-intercept. Then find another point that lies on the grid.
y=1/2x-1
Practice makes perfect
Equations written in slope-intercept form follow a specific format, where m is the slope of the line and b is the y-intercept.
y= mx+b
We need to identify these values using the graph. Let's start with the y-intercept.
Finding the y-intercept
The y-intercept is the y-value where the line crosses the y-axis.
We can see that the function crosses the y-axis at (0, -1). This means that the value of b is -1.
y= mx+( - 1) ⇔ y= mx - 1
Finding the Slope
To find the slope, we will trace along the line on the given graph until we find a lattice point. In doing so, we will be able to identify the slope m using the rise and run of the graph.
Here we've identified the x-intercept at (2,0) as our other point. Traveling to this point from the y-intercept requires that we move 1 step vertically in the positive direction, and 2 steps horizontally in the positive direction.
rise/run=1/2 ⇔ m= 1/2
Writing the Equation
Now that we have the slope and the y-intercept, we can form our final equation.
y= 1/2x - 1
