Math 1 · Unit 9 · Lesson 1 · part 2 of 5
Two families, now as lists
This unit has almost no new math in it.
Two families, now as lists
This unit has almost no new math in it. It takes the two families you already know, lines from Unit 3 and exponentials from Unit 7, and writes them as lists. Here is the side-by-side table from Unit 8, Lesson 2: $1,000 at 5%, simple interest on the left and compound interest on the right. Read each column as a list of balances.
Those two columns have names. A list that adds the same amount each time is an arithmetic sequence (say air-ith-MET-ik). A list that multiplies by the same number each time is a geometric sequence.
Adding gives arithmetic, multiplying gives geometric. An arithmetic sequence is the line family in list form: its points fall on a line. A geometric sequence is the exponential family in list form: its points fall on an exponential curve. Lines add, exponentials multiply, and now lists do too.