# Sequence and series

### Sequence and series (Questions)

*Notes:*

*The nth term in an arithmetic progression is: an = a + (n-1)d*

*sum of the nth terms in an arithmetic progression is Sn = n/2(2a + (n-1)d)*

A. Solve the following arithmetic progression questions.

- If the 10th term is 21 while the 12nd term is 25, what is the common difference (d) and also the second terms of the series.
- Find the 10th term of the series (Given that the sum of the nth terms in an arithmetic progression is Sn = 3n + n
^{2}).

### Sequence and series (Answers)

- d = 2, a2 = 5
- a5 = 22

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