1. Warm-Up
Write the next term in the series. Then write the series with summation notation. 5 n 3n -1
n=1

2. Agenda: 4/02/15 1.) Warm-up 2.) Questions:
Objective: (1) Using and Writing Sequences (2) Using Series
Agenda: 4/02/15
1.) Warm-up
2.) Questions:
WS 11.1 Practice A #’s 1-27 ODD (Skip 11&13)
WS 11.1 Practice B #’s 1-25 ODD (Skip 11)
3.) Lesson: 11.2 Arithmetic Sequences and Series
4.) Class/Homework
5.) Work in Pairs/Groups
STAY ON TASK!!

3. 11.2 Arithmetic Sequences and Series (Day 1)
In an Arithmetic Sequence, the difference between consecutive terms is constant.
The constant difference is called the common difference and is denoted by d.
Ex. 1 Decide whether the sequence is arithmetic. Explain why or why not.
- 3, 1, 5, 9, 13, …
To decide whether a sequence is arithmetic, find the differences of consecutive terms.
d = 1 – (- 3) = 4 d = 5 – 1 = 4 d = 9 – 5 = 4 d = 13 – 9 = 4
Each difference is 4, so the sequence is arithmetic.

4. 11.2 Arithmetic Sequences and Series (Day 1)
RULE FOR AN ARITHMETIC SEQUENCE
The nth term of an arithmetic sequence with first term a1 and common difference d is given by:
an = a1 + (n – 1)d
Ex. 2 Write a rule for the nth term of the arithmetic sequence. Then find a25.
50, 44, 38, 32, …
a1 = 50 and d = 44 – 50 = - 6, so the sequence is arithmetic. A rule for the nth term is:
Memorize!!

5. 11.2 Arithmetic Sequences and Series (Day 1)
Ex. 3 Write a rule for the nth term of the arithmetic sequence.
d = 4, a14 = 46
In order to write the nth term the “d” and the “a1” ARE NEEDED. To find a1 use the a14 and the following rule.
an = a1 + (n – 1)d
a14 = a1 + (14 – 1)(4)
46 = a1 + 52
- 6 = a1
an = (n – 1)(4)
an = n – 4
an = 4n – 10
Memorize!!

6. 11.2 Arithmetic Sequences and Series (Day 1)
Ex. 4 Write a rule for the nth term of the arithmetic sequence.
a5 = 17, a15 = 77
In order to find the nth term WE NEED to find the a1 and the d.
We use the a5 and the a15 terms in the nth term for an arithmetic sequence.
an = a1 + (n – 1)d
Memorize!!

7. 11.2 Arithmetic Sequences and Series (Day 1)

8. HOMEWORK
This is FUN!!!!!
Page ALL