Question

Use the points (2, 2485.6) and (6, 1172.5) to write an equation of the line of fit in slope-intercept form. Let x be the years since 2010 and let y be the number of CDs in millions sold.

Answer 1

the person above me is wrong!

(answer is in the picture)

Answer 2

y = -328.275x + 1829.05

Explanation:

In this case, we need to write an equation of this form:

y = ax + b (1) a: slope b: intercept

In order to calculate the slope, we need to use the following expression:

a = y₂ - y₁ / x₂ - x₁ (2)

So, we have two points here, so, from these points we can identify each of the elements so we can determine the slope.

Point 1: (2, 2485.6)

Point 2: (6, 1172.5)

The slope of this equation will be:

a = 1172.5 - 2485.6 / 6 - 2

a = -328.275

Now that we have the slope, to get the intercept "b", we just use any of the given points, and replace in the general equation (1) to solve for b:

2485.6 = -328.275(2) + b

b = 2485.6 - 656.55

b = 1829.05

With the value of a and b, we can write the general equation of the line for this:

y = -328.275x + 1829.05

Hope this helps