Question

1. Here are the first 5 terms of an arithmetic sequence.

2
9
16
23
30
a) Find, in terms of n, an expression for the nth of this sequence.
Answer:

b) Write down the 15th term of this sequence.
Answer..​

Answer 1

see explanation

Explanation:

The n th term of an arithmetic sequence is

`a_(n)` = a₁ + (n - 1)d

where a₁ is the first term and d the common difference

Here a₁ = 2 and d = 9 - 2 = 7, thus

(a)

`a_(n)` = 2 + 7(n - 1) = 2 + 7n - 7 = 7n - 5

(b)

Using the n th term formula, then

`a_(15)` = 7(15) - 5 = 105 - 5 = 100