PATTERNS, FUR1 2011 VCAA 8 MC

The first three terms of an arithmetic sequence are `1, 3, 5 . . .`

The sum of the first `n` terms of this sequence, `S_n`, is

A. `S_n = n^2`

B. `S_n = n^2 - n`

C. `S_n = 2n`

D. `S_n = 2n - 1`

E. `S_n = 2n + 1`

Show Answers Only

`A`

Show Worked Solution

`text(Sequence is 1, 3, 5 , . . .)`

♦ Mean mark 38%.

`text(AP where)\ \ \ a`	`= 1, and`
`d`	`= 3 – 1 = 2`

`=> A`