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VCE 12 General 2023

5.01 First order recurrence relations

Worksheet
Sequences
1

Consider the sequences defined by the following recursive rules. State the first 5 terms of the sequence:

a

a_{0} = 7 and a_{n + 1} = a_{n} + 5 for n \geq 0

b

a_{0} = 100 and a_{n + 1} = a_{n}-10 for n \geq 0

c

a_{0} = 2 and a_{n + 1} = 4 a_{n} for n \geq 0

d

a_{0} = 2 and a_{n + 1} = 0.5 a_{n} - 7 for n \geq 0

e

a_{0} = 3 and a_{n + 1} = 3 a_{n} - 3 for n \geq 0

f

a_{0} = 54 and a_{n + 1} = \dfrac{1}{3} a_{n} for n \geq 0

2

Consider the sequences defined by the following explicit rules. State the first 5 terms of the sequence:

a

a_{n} = 2n + 1 for n \geq 0

b

a_{n} = 18- 2n for n \geq 0

c

a_{n} = 3 n for n \geq 0

d

a_{n} = - 4 \left(n - 1\right) for n \geq 0

e

a_{n} = 2^{n + 2} for n \geq 0

f

a_{n} = \left( - 3 \right)^{n + 3} for n \geq 0

3

Consider the sequence represented in the table:

a

State the type of sequence.

b

Find x_{10}.

n56789
x_{n}- 23- 27- 31- 35- 39
4

Complete the sequences in the tables with the given conditions below:

a

x_{n} is arithmetic.

n45678
x_{n}412
b

y_{n} is geometric.

n45678
y_{n}412
5

Consider the recurrence relation u_{n + 2} = u_{n + 1} + u_{n}.

Complete the table for the first 10 terms in the sequence where u_{0} = 1 and u_{1} = 1:

n0123456789
u_{n}
Explicit and recursive rules
6

For each of the following sequences, write a recursive rule for a_{n + 1} in terms of a_{n} and an initial condition for a_{0}:

a
3, 7, 11, 15, \ldots
b
5, 10, 20, 40, \ldots
c
81, 27, 9, 3, \ldots
d
10, 7.5, 5 , 2.5 , \ldots
7

For each of the following sequences, write a formula for the n \text{th} term, a_{n}, in terms of n:

a
2, 8, 14, 20, \ldots
b
4, 12, 36, 108, \ldots
c
3, 0.3, 0.03, 0.003, \ldots
d
4.5, 2, - 0.5 , - 3 , \ldots
8

For each of the following sequences, write a recursive rule for a_{n + 1} in terms of a_{n} and an initial condition for a_{1}:

a

a_{n} = 7+3\left(n-1\right)

b

a_{n} = 8-2\left(n-1\right)

c

a_{n} = 2n+3

d

a_{n} = 8- n

e

a_{n} = 1.5n+6

f

a_{n} = - 5 + 7 n

g

a_{n} = 5 \left(2\right)^{n-1}

h

a_{n} = 20\left(1.1\right)^{n - 1}

i

a_{n} = 100 (0.5)^{n-1}

j

a_{n} = - 5 \left(4.8\right)^{n - 1}

9

For each of the following sequences, write a formula for the n \text{th} term of the sequence, a_{n}, in terms of n:

a

a_{1} = 15, a_{n + 1} = a_{n} +2 for n \geq 1

b

a_{1} = -9, a_{n + 1} = 2a_{n} for n \geq 1

c

a_{1} = - 13, a_{n + 1} = a_{n} - 8 for n \geq 1

d

a_{1} = 17, a_{n + 1} = - 4.7 a_{n} for n \geq 1

10

For each of the following, write t_n in terms of n:

a

t_{n + 1} = t_n - 9 where t_0 = 2.

b

t_{n + 1} = 2 t_{n} where t_0 = 5

c

t_{n + 1} = t_{n}+4 where t_{0} = 7.

d

t_{n + 1} = - t_{n} where t_{0} = 6.

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Outcomes

U3.AoS2.1

the use of first-order linear recurrence relations to model growth and decay problems in financial contexts

U3.AoS2.5

model and analyse growth and decay in financial contexts using a first-order linear recurrence relation

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