Identify the y-intercept. Use the two given points to calculate the slope.
y=-2/5x-1
Practice makes perfect
Equations written in slope-intercept form follow a specific format.
y= mx+ b
In this form, m is the slope and b is the y-intercept. We need to identify these values using the graph and the two given points.
y-intercept
The y-intercept is the y-value where the line crosses the y-axis.
We can see that the function intercepts the y-axis at (0, - 1). This means that the value of b is - 1.
y= mx+( - 1)
Slope
To find the slope, we will consider the two given points and identify the slope m using the rise and run of the graph.
Here we have (5,-3) as our other given point. Traveling to this point from the y-intercept requires that we move 5 steps horizontally in the positive direction and 2 steps vertically in the negative direction.
rise/run=-2/5 ⇔ m= -2/5
Writing the Equation
Now that we have the slope and the y-intercept, we can write our final equation.
y= -2/5x+( -1) ⇒ y=-2/5x-1
