1. Lesson 4.3: Using Recursive Formulas
Advanced Math Topics

2. Definition of Recursive Formula
The formula for a sequence that tells you how to find the nth term from the term(s) before it.

3. Example/Steps Part 1: the value of the 1st term(s) are given
Part 2: A recursion equation shows how to find each term from the term before it.
an=2an-1
Part 3: Plug numbers into the formula to find the next terms in the sequence.
a2=2a2-1=2a1=2(1)=2
a3=2a3-1=2a2=2(2)=4
a4=2a4-1=2a3=2(4)=8

4. Examples
a1=12
an=3(an-1) n

5. Examples
a1=3
a2=2
an=an-1-2an-2

6. Examples
a1=1
a2=2
an=(an-2)2-(an-1)2

7. Examples
a1=10
an= 1
an-1

8. Word Problem
Start January by plugging in 0 for an-1 and then fill in chart

9. Homework
Page 225/ 8-13
Remember that i is an imaginary number and i2 = -1