Question

At the start of summer vacation, Wesley decides to learn a number of kanji characters each week. The total number of characters Wesley knows, y, is a function of the number of weeks, I. The graph of the function passes through the points (3, 120) and (5, 160).
Find and describe the rate of change of the function.
>The rate of change is 20. It represents
the number of characters Wesley
learns each week
Find and describe the initial value of the function.
The initial value is
X
X

Answer 1

Slope = (160 − 120)/(5 − 3) = 40/2 = 20.
It means Wesley learns 20 characters per week.

Initial value: set y = 20I + b. Using (3,120): 120 = 60 + b so b = 60.
The initial value is 60 — Wesley knew 60 characters at week 0.