1. Daily Check Find the first 3 terms of the following sequence:
Write the formula for the following arithmetic sequence.
-2, 1, 4, 7, 10

2. How is a geometric sequence like an exponential function?
Math II
UNIT QUESTION: How is a geometric sequence like an exponential function?
Standard: MM2A2, MM2A3
Today’s Question:
How is a geometric sequence like an exponential function?
Standard: MM2A3f,g

3. Sequences and Series

4. Geometric Sequences
In geometric sequences, you multiply by a common ratio each time.
1, 2, 4, 8, 16, ...
multiply by 2
27, 9, 3, 1, 1/3, ... Divide by 3 which means multiply by 1/3

5. Geometric Sequences Find the 8th term of the sequence: 2,6,18,…
Determine the pattern:
Multiply by 3 (known as the common ratio)
Write the new sequence:
2,6,18,54,162,486,1458,4374
So the 8th term is 4374.

6. Geometric Sequences Again, use a formula to find large numbers.
        an = a1 • (r)n-1

7. Geometric Sequences Find the 10th term of the sequence : 4,8,16,…
an = a1 • (r)n-1
a1 = 4
r = 2
n = 10

8. Geometric Sequences an = a1 • (r)n-1 a10 = 4 • (2)10-1 a10 = 4 • (2)9

9. Geometric Sequences Find the ninth term of a sequence if
a3 = 63 and r = -3
a1= ?
n= 9
r = -3
a9 = ?
There are 2 unknowns so you must…

10. Geometric Sequences First find t1.
Use the sequences formula substituting t3 in for tn.  a3 = 63
a3 = a1 • (-3)3-1
63 = a1 • (-3)2
63= a1 • 9
7 = a1

11. Geometric Sequences Now that you know t1, substitute again to find tn.
an = a1 • (r)n-1
a9 = 7 • (-3)9-1
a9 = 7 • (-3)8
a9 = 7 • 6561
a9 = 45927

12. Class work Day 1: Workbook p. 159 #1-9, 13-15, 19 odd

13. Homework
Page 145 #2-16 (even)