1. What comes next?
An arithmetic
3, 5, 7, 9, 11 13 15
__, __, __ sequence is a
pattern of
+2 +2 +2 +2 +2 +2
numbers in
Common difference which each
d=2 number is
a1 = 3 found by adding
a constant to
a2 = 5 the number
before it.
a3 = 7

2. What’s the common difference?
8, 10.5, 13, 15.5, …
d = 2.5
9, 5, 1, -3, …
d = -4

3. 3, 5, 7, 9, 11, 13, 15, …
+2 +2 +2
a1 = 3
a2 = 5 3 + 1(2)
a3 = 7 3 + 2(2)
a4 = 9 3 + 3(2)
an = a1 + (n – 1)d

4. Write an equation for the nth term of the
arithmetic sequence –8, –6, –4, ….
Find the 80th term of the sequence
a80 = 2(80) – 10
= 160 – 10
= 150

5. Complete the statement for the arithmetic sequence:
124 is the ____ term of -2, 5, 12, …
124 -2 7
124 = -2 + 7n – 7
124 = 7n – 9
133 = 7n
19 = n

6. The terms between any two nonconsecutive
terms of an arithmetic sequence are arithmetic
means.
Find the three arithmetic means between 21 and 45.
27 33 39
21, ___, ___, ___, 45, ...,
+d +d +d +d