hvvrq $ulwkphwlf 6htxhqfhv dqg 6hulhv - NCPN
hvvrq $ulwkphwlf 6htxhqfhv dqg 6hulhv - NCPN
hvvrq $ulwkphwlf 6htxhqfhv dqg 6hulhv - NCPN
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INSTRUCTION<br />
Example 2 Return to<br />
the spreadsheet used at the<br />
beginning of class. Remind<br />
students of the formulas that<br />
they created to represent the<br />
amount of savings in Maryanne’s<br />
account. Ask students to classify<br />
the formulas as being recursive or<br />
explicit.<br />
Ask students to identify which<br />
method of defining a sequence<br />
they prefer if given a choice. Ask<br />
students to justify their answers.<br />
Think and Discuss<br />
Answers<br />
1. No, the value of a 1<br />
is not<br />
known.<br />
2. Answers will vary. Sample<br />
answer: a sequence is an<br />
ordered list of numbers such<br />
as 2, 4, 6, 8, 10, …<br />
3. An explicit formula is given by<br />
a rule that does not depend<br />
on other terms of the pattern.<br />
A recursive formula generates<br />
terms of the pattern based on<br />
previous terms.<br />
4. The formula is explicit since<br />
a n<br />
does not depend on a<br />
previous term.<br />
5. Substitute 8 for n in the<br />
expression and simplify.<br />
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R.E.A.C.T. Strategy<br />
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Introduce students to the classic handshake problem. Challenge students to<br />
determine how many handshakes would take place in a roomful of 20 people.<br />
Ask students to justify their answers and to identify if they used an explicit or<br />
recursive formula when solving the problem.<br />
394 Chapter 9 Sequences and Series