7A-6 Arithmetic Sequences - White Plains Public Schools

SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
Do Now:
​
1)​ ​ Write a rule for each arithmetic sequence. Then find ​a3​ 0. ​ ​
​
a)​ ​ 4, 7, 10, 13…
​
​
​
​
b) -2, -6, -10, -14…. ​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
Given two terms in a sequence write an equation for the nth term ​
1)​ ​
a)
The 4th term of a sequence is 80 and the
12th term is 32.
Write an equation for the nth term of the sequence.
1
SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
b)
The 2nd term of a sequence is 5.25 and the
10th term is –0.75.
Write an equation for the nth term of the sequence.
c)
The 3rd term of a sequence is 39 and the 20th term is 260.
Write an equation for the nth term of the sequence.
2
SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
Arithmetic Sequence Word Problems ​
​
2)​ ​ Leslie, a very perceptive young lady, noticed that the number of text messages she received ​
over the course of two months formed an arithmetic sequence. If she received 13 messages ​
on day 3 and 64 messages on day 20: ​
​
a)​ ​ How many messages did she receive on day 12? ​
​
​
​
​
​
​
​
​
​
b)​ ​ How many messages did she receive on day 50? ​
​
​
​
​
​
​
​
​
​
​
3)​ ​ In an auditorium, the first row of seats has 30 seats. Each row behind the first row has 4 ​
more seats than the row in front of it. How many seats are in the 25th row? ​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
3
SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
​
4)​ ​ ​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
5)​ ​ ​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
4
SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
LESSON PRACTICE
​
In Exercises 9 & 10, find the common difference of the arithmetic sequence. ​
​
9. 6
​ .5, 5, 3.5, 2, . . .
​
​
​
​
10. −
​ 16, −7, 2, 11, . . . ​
​
​
In Exercises 14 & 15, write the next three terms of the arithmetic sequence. ​
​
14. 6
​ 0, 30, 0, −30, . . .
​
​
​
​
15. 1
​ .3, 1, 0.7, 0.4, . . . ​
​
​
In Exercises 27 & 29, determine whether the sequence is arithmetic. If so, find the ​
common difference. ​
​
27. 1
​ 3, 26, 39, 52, . . .
​
​
​
​
​
29. 4
​ 8, 24, 12, 6, . . . ​
​
​
​
42.​ The first row of a dominoes display has 10 dominoes. Each row after the first has two ​
more dominoes than the row before it. Write the first five terms of the sequence that represents ​
the number of dominoes in each row. ​
​
​
​
​
​
​
​
​
45.​ The total number of babies born in a country each minute after midnight January 1st can be ​
estimated by the sequence shown in the table. ​
​
​
​
​
​
a. W
​ rite a function that represents the arithmetic sequence. ​
​
​
​
​
​
b. E
​ stimate how many minutes after midnight January 1st it takes for 100 babies to be born.​ ​
​
​
​
​
​
​
5
SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
LESSON PRACTICE ANSWER KEY
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
6
SWBA T: Write the terms of an arithmetic sequence. Write arithmetic sequences as functions.
Lesson 7A -6
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
​
7