In this equation, m is the slope and b is the y-intercept. To find the slope m, we will first choose any two points on the line. Let's try to choose points that have coordinates that are easy to identify.
The first point has the coordinates x_1= 3.5 and y_1= 8000. The second point has the coordinates x_2= 5 and y_2= 7000. Let's substitute these values into slope formula.
We found that the slope m is equal to about -667. This means that the cost to own a certain car decreases by about 667 dollars per year.
y=mx+b ⇔ y= -667x+b
Now we will find the y-intercept b, which is the y-value when x=0. We can find it on the graph!
We can see that when x=0, the y-value is equal to about 10 400. Therefore, the y-intercept b is also equal to about 10 400. This means the initial cost to own the car is equal to about 10 400 dollars.
y=-667x+b ⇕ y=-667+ 10 400
We wrote an equation of the line in slope-intercept form! Notice that this is just one example equation. Other equations based on other points or other lines of best fit are also acceptable.
