Question

The following graph shows the relationship established by a car dealership between the sale price of a particular car model and the age of the car.

Write the equation for the line of best fit shown on the graph.

Y=

Answer 1

y = -2444.4444x+19000

Explanation:

Pick two points along the line to find the slope

(0, 19000) and (4.5, 8000)

slope = (y2-y1)/(x2-x1)

= (8000-19000)/(4.5-0)

=-11000/4.5

= -2444.44444444

We know the y intercept (where it crosses the y axis (x=0)) (0, 19000)

We can write an equation using y = mx+b

y = -2444.4444x+19000

Answer 2

Using 2 points: (0,19,000) and (3.25, 11,000)

First find the slope by putting the change in Y over the change in X:

Slope = ( 19000 - 11000) / (0 - 3.25)

Slope = -2462.54

The Y intercept is the 1st Y value = 19,000

The equation becomes: y = -2461.54x + 19000