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3.02 Sequences and their defining rules - calculator assumed

Worksheet
Sequences
1

Given the following sequences, find the indicated term:

a

The 53^\text{rd} term in: 2, 3.5, 5, 6.5, 8, 9.5, \ldots

b

The 21^\text{st} term in: - 3 , - 6 , - 9 , - 12 , - 15 , \ldots

c

The 39^\text{th} term in: 10, 8, 6, 4, 2, 0, - 2 , \ldots

2

Calculate:

a

T_3 + T_5 for the sequence: 6, - 8 , 9, - 10 , 11, \ldots

b

2 T_2 - T_4 for the sequence: 9, 12, 15, 18, 21, \ldots

c

- 4 \left(T_3 + T_4\right) for the sequence: 1, 4, 5, 9, 14, 23, \ldots

3

Consider the sequence 5, - 5 , 7, - 7 , 9, - 9 , \ldots Find n if T_n = 7.

Recursive rule
4

Consider the sequence which has a first term of 11 and a second term of 22, and subsequent terms are found by adding the two previous terms.

a

Write the recursive rule for the sequence, letting T_n be the n\text{th} term.

b

State the first five terms of the sequence.

5

For the following recursive relations, find:

i

T_2

ii

T_3

iii

T_4

a

T_n = n^{n + 1} + T_{n - 1}, T_1 = 3

b

T_{n + 1} = \left( 4 T_n\right)^{n - 1} \times \left(n + 1\right), T_1 = 5

6

Consider the sequence defined by a_n = 2 a_{n - 1} + 3, a_1 = 12. Calculate the sum of the first 25 terms.

7

Consider the sequence defined by b_{n+1} = 1.8 b_n + 50, b_1 = 1. Calculate the sum of the terms from the 20th term to the 29th term inclusive. Round your answer to the nearest whole number.

8

Consider the sequence T_n = T_{n - 1} + 5, T_1 = 10

a

Find T_{40}.

b

Find the first term greater than or equal to 300.

c

If S_n is the sum of the first n terms, find S_{30}.

d

Starting from n = 1, find the minimum number of terms for the sum to be greater than 5000.

9

Consider the sequence T_{n+1} = 1.5 T_n, T_1 = 10

a

Find T_{10} to the nearest whole number.

b

Find the first term greater than or equal to 1000. Round your answer to the nearest whole number.

c

If S_n is the sum of the first n terms, find S_{18}. Round your answer to the nearest whole number.

d

Starting from n = 1, find the minimum number of terms for the sum to be greater than 50\,000.

10

For each pair of sequences, compare the first 10 terms of each of these sequence on a graph to determine which sequence is increasing faster:

a

T_{n + 1} = 2.5 T_n, T_1 = 5 and A_{n + 1} = 3.5 A_n, A_1 = 5

b

T_{n + 1} = T_n + 22,T_1 = 12 and A_{n + 1} = A_n + 25, A_1 = 12

11

For each pair of sequences, compare the first 10 terms of each of these sequence on a graph to determine which sequence is decreasing faster.

a

T_{n + 1} = T_n - 5,T_1 = 4 and A_{n + 1} = A_n - 10, A_1 = 12

b

T_{n + 1} = 0.2 T_n, T_1 = 20 and A_{n + 1} = 0.6 A_n, A_1 = 20

Explicit rule
12

For the explicit rule T_n = 0.7 n - 5 which starts at n = 1, find the sum of the first 50 terms.

13

For the explicit rule T_n = \left( 0.2 n\right)^{2} + 5 n which starts at n = 1, find the sum of the terms from the 20th to the 30th term inclusive.

14

Consider the sequence given in the table below:

a
Write the general rule for T_n in terms of n.
b

Use the general rule to find T_{20}

n1234...
T_n14916...
15

Consider the sequence given in the table below:

a
Write the general rule for T_n in terms of n.
b

Use the general rule to find T_{19}.

n1234...
T_n182764...
16

Consider the sequence T_n = 5 - 3 n, starting at n = 1:

a

Find T_{30}.

b

Find the first term less than - 150.

c

If S_n is the sum of the first n terms, find S_{15}.

d

Starting from n = 1, find the minimum number of terms required for the sum to be less than - 600.

17

Consider the sequence 3, 7, 11, 15, 19, 23, \ldots

a

If T_n is the value of the nth term in the sequence, find T_{10}.

b

Find the first term greater than 100.

c

If S_n is the sum of the first n terms, find S_{10}.

d

Starting from n = 1, find the minimum number of terms for the sum to first exceed 500.

18

Consider the sequence 1, 2, 4, 8, 16, \ldots

a

Find T_{13}.

b

Find the first term greater than 10\,000.

c

If S_n is the sum of the first n terms, find S_{20}.

d

Starting from n = 1, find the greatest number of terms such that the sum is still less than 10\,000\,000.

19

Consider the sequence T_n = 200 \times 0.5^{n - 1}

a

Find T_8.

b

Find the first term less than 0.5.

c

If S_n is the sum of the first n terms, find S_{10}.

d

Starting from n = 1, find the minimum number of terms for the sum to first exceed 399.9.

20

For the following sequences:

i

State the recursive rule that describes T_n in terms of T_{n - 1}, and the initial term T_1.

ii

State the explicit rule that describes T_n in terms of n.

a

A sequence starts with a first term of 1300 and each subsequent term increases by 2.5\% of the previous term.

b

A sequence starts with a first term of 44 and each term is 77 more than the previous term.

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