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11.2 Arithmetic Sequences.notebook
1
April 27, 2017
11.2: Arithmetic Sequences Date: 4/27
An Arithmetic Sequence is a sequence in which each term after the first differs from the preceding term by a constant amount. The difference between consecutive terms is called the common difference, denoted d, of the sequence.
The value of d is found by subtracting any term from the term that directly follows it.
Ex:
The graph of an arithmetic sequence forms a set of discrete points lying on a straight line. This illustrates that an arithmetic sequence is a linear function whose domain is the set of positive integers.
Ex: Position Term
1 10
2 15
3 20
4 25
5 30
6 35
11.2 Arithmetic Sequences.notebook
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Ex 1: Write the first six terms of the arithmetic sequence in which and
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General Term of an Arithmetic Sequence
The nth term (the general term) of an arithmetic sequence with first termand common difference d is
Ex 2: Write a formula for the nth term of the arithmetic sequence in Ex 1.
Ex 3: Find the ninth term of the arithmetic sequence whose first term is 6 and whose common difference is ‐5.
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Ex 4: Thanks to drive‐thrus and curbside delivery, Americans are eating more meals behind the wheel. In 2004, we averaged 32 a‐la‐car meals, increasing by approximately 0.7 meals per year.
a) Write a formula for the nth term of the arithmetic sequence that models the average number of car meals n years after 2003.
b) How many car meals will Americans average by the year 2020?
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The sum of the first n terms of an arithmetic sequence, denoted _______, and called the nth partial sum, can be found without having to add up all the terms.
Ex 5: Find the sum of the first 15 terms of the arithmetic sequence: 3, 6, 9, 12, …
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Ex 7: Company A pays $24,000 yearly with raises of $1600 per year. Company B pays $28,000 yearly with raises of $1000 per year. Which company will pay more in year 10? How much more?
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Ex 8: You are considering two job offers. Company A will start you at $19,000 a year and guarantee a raise of $2600 per year. Company B will start you at a higher salary, $27,000 a year, but will only guarantee a raise of $1200 per year. Find the total salary that each company will pay over a ten‐year period. Which company pays the greater total amount?
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Ex 9: A section in the stadium has 20 seats in the first row, 23 seats in the second row, increasing by 3 seats each row for a total of 38 rows. How many seats are in this section of the stadium?