Question

(05.03 MC)

Answer 1

Part A:

To find the rate of change:

m = (150 - 120) / (0 - 1) because the slope formula is:

m = ($y_{2} - y_{1}$) / ($x_{2} - x_{1}$)

m = (150 - 120) / (0 - 1) is equal to:

m = 30/-1
Or -30.

So the rate of change is -30. 

The initial value is just 150, because as the x value is 0, the y value is 150.

The rate of change represents how she has to download 30 less songs onto her music player each week. The initial value means she originally had 150 songs she needed to download.

Part B:

Slope intercept form is y = mx + b.

In this case, we already can figure out everything because the y intercept is said, when it says a straight line joins the ordered pairs 0, 150,  and 1, 120... etc.

So since the x value in that point was 0, we then know that that 150 must be the y intercept.

So since we know the slope, m, as well (-30) we can just fit everything into this equation.

y = -30x + 150