Question

whta is the sum of the first 30 terms of this arithmetric sequence? 6,13,20,27,34

Answer 1

A.3225
B.3255
C3325
D.3525

Answer 2

If I'm correct, it should be 3225, so A.

I think you can write out the series as

\[\sum_{i=1}^{30}6+(i-1)7\]

And then you can find the last number in the series, which is 209.

Add 209 and the first term, 6, then multiply by half of the terms.

\[\frac{ 30 }{ 2 } (209+6)\]