12 General Unit 3 Topic 4 - Growth and Decay in Sequences

Which of the following could be the first five terms of an arithmetic sequence?

• 2, 4, 2, 4, 2

• 1, 10, 100, 1000, 10 000

• -189, -89, 11, 111, 211

• 1, 4, 9, 16, 25

• 4, 4, 6, 6, 8

Which of the following is NOT an arithmetic sequence?

• 11, 2, -8, -19, ...

• 4, 7, 10, 13, ...

• 57, 51, 45, 39, ...

• -3, -5, -7, -9, ...

• 1, 2, 3, 4, ...

The first term of a sequence is 3. Each subsequent term is 0.6 times the previous term. What is the sixth term correct to two decimal places?

• 0.14

• 0.23

• 6.92

• 7.15

• 7.5

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The ninth term of the arithmetic sequence 44, 41, 38, ..., is:

• 8

• 17

• 20

• 23

• 26

The following is a geometric sequence 15, -45, 135, -405,... The common ratio, r, is equal to:

• -3

• -2

• 1

• 2

• 3

• 73

• 75

• 85

• 297

• 1193

The rungs of a ladder diminish uniformly in length from 30 cm at the bottom of the ladder to 22.5 cm at the top of the ladder. There are 16 rungs altogether. The length, in cm, of the 10th rung up the ladder is:

• 24.5

• 25.0

• 25.3

• 25.5

• 25.8

• 5, 15, 45, 135, 405, ...

• 5, 8, 11, 14, 17, ...

• 5, 2, -1, -4, -7, ...

• 5, 15, 45, 135, 405, ...

• 5, -15, 45, -135, 405, ...

Brian has two trees in his backyard. Every month, he will plant three more trees. A recurrence relation model, Tn, for the number of trees in Brian's backyard at the start of the month, n, is:

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