Page 2 - Number sequence

Rules used to determine terms in a sequence.

Question
Given the sequence: 3; 6; 9; 12; 15; ... .
th
i. Write down the general rule for the n term of the sequence.
th
ii. Hence determine the 78 term.

Solution
th
i. 3 is added on the previous term to obtain the next term starting from 3. ∴ n term = 3n

or

Term 1 3 × (1) = 3 3

Term 2 3 × (2) = 6 6

Term 3 3 × (3) = 9 9

Term 4 3 × (4) = 12 12

Term 5 3 × (5) = 15 15

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Term n 3 × (n) = 3n 3n

th
th
ii. If n term = 3n then 78 term = 3×78 = 234