Applied 20S January 7, 2009

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Next in sequence? by flickr user the mad LOLscientist

description

Arithmetic sequences and applications.

Transcript of Applied 20S January 7, 2009

Page 1: Applied 20S January 7, 2009

Next in sequence? by flickr user the mad LOLscientist

Page 2: Applied 20S January 7, 2009

Sequence: An ordered list of numbers that follow a certain pattern (or rule).

Arithmetic Sequence: (i) Recursive Definition: An ordered list of numbers generated by continuously adding a value (the

common difference) to a given first term.(ii) Implicit Definition: An ordered list of numbers where each number in the list is generated by a linear equation.

Some Definitions

Common Difference (d): (i) The number that is repeatedly added to successive terms in an arithmetic sequence.

(ii) From the implicit definition, d is the slope of the linear equation.

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Example: Find the 51st term (t51) of the sequence 11, 5, -1, -7, ...

Solution: a = 11 t51 = 11 + (51 - 1)(-6) d = 5 - 11 t51 = 11 + (50)(-6) = -6 t51 = 11 - 300 n = 51 t51 = -289

tn is the nth terma is the first termn is the "rank" of the nth term in the sequenced is the common difference

tn = a + (n - 1)d

To Find the nth Term In an Arithmetic Sequence

d is the common differencetn is an arbitrary term in the sequencet(n - 1) is the term immediately before tn in the sequence

d = tn - t(n - 1)

To Find The Common Difference

Implicitly

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Which of the following sequences are arithmetic sequences?

HOMEWORKa) 1, 2, 6, 24, 120,…

b) 3, 9, 15, …

c) 2, 4, 8, 16, 32,…

d) 1, 2, 3, 5, 8, 13, …

e) -4, -1, 2, 5, 8,…

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What is the pattern in the sequence 2, 8, 14, 20, 26…?Suggest an equation that could be used to generate such a list.

HOMEWORK

2, 8, 14, 20, 26

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a) Why do the numbers 5, 8, 11, 14, 17… form an arithmetic sequence?

b) What is the defining equation that produced them?

c) What is the 27th term of this sequence?

HOMEWORK

5, 8, 11, 14, 17

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a) What is the next term of the sequence 1, -1, -3, -5, -7,…?

b) Find an equation that could be used to generate such a sequence.

c) What is the 35th term of this sequence?

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Harriet wants to phone her aunt in England to give her some family news. The first minute of the phone call costs $3.60 and each additional minute costs $0.12.

Set up an equation that could be used to define this relationship.

Use the equation to calculate how much it would cost to talk for 28 minutes.

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List the first 4 terms of the sequence determined by each of the following implicit definitions.

(a)

(b)

(c)

(d)

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Determine which of the following sequences are arithmetic. If a sequence is arithmetic, write the values of a and d.

(a) 5, 9, 13, 17, ...

(b) 1, 6, 10, 15, 19, ...

(c)-1, -4, -7, -10, ...

(d) x, 2x, 3x, 4x, ...

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Given the values of a and d, write the first 5 terms of each arithmetic sequence.(a) a = 7, d, = 2

(b) a = -4, d, = 6

(c) a = 8, d, = x

(d) a = 3m, d, = 1 - m

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Find the indicated terms for each arithmetic sequence.

(a) 6, 8, 10, ... t and t10 4

(b) 9, 16, 23, ... t and t18 41

(c) -4, -9, -14, ... t and t18 66

(d) x, x + 4, x + 8, ... t and t14 n

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Find the number of terms in each of the following arithmetic sequences.

(a) 10, 15, 20, ..., 250

(b) 40, 38, 36, ...-30

(c) -2, -8, -14, ..., -206

(d) x + 2, x + 9, x + 16, ... , x + 303

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Complete each arithmetic sequence by finding the missing arithmetic means.(a) 1, ____, 25

(b) 14, ____, ____, 32

(c) -3, ____, ____, -60

(d) -1.5, ____, ____, ____, 4.5

(e) 2, ____, ____, ____, ____, 107

(f) m + 40, ____, ____, ____, m + 4

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The eighth term of an arithmetic sequence is 5.3 and the fourteenth term is 8.3. What is the fifth term?

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Answers to the last 7 questions:1. (a) 0, 3, 6, 9 (b) 0, 1, 4, 9 (c) 1, 2, 4, 8 (d)

2. (a) 5, 4 (b) not arithmetic (c) -1, -3 (d) x, x

3. (a) 7, 9, 11, 13, 15 (b) -4, 2, 8, 14, 20(c) 8, 8 + x, 8 + 2x, 8 + 3x, 8 + 4x (d) 3m, 2m + 1, m + 2, 3, 4 - m

4. (a) 24, 72 (b) 65, 702 (c) -89, -329 (d) x + 4(n - 1), x + 52

5. (a) 49 (b) 36 (c) 35 (d) 44

6. (a) 13 (b) 20, 26 (c) -22, -41

(d) 0, 1.5, 3 (e) 23, 44, 65, 86 (f) m + 31, m + 22, m + 13

7. 3.8