Question

Find S12 for 1 + 6 + 11 + 16 +…

Answer 1

looks like an arithmetic series..

Answer 2

what have you tried?

Answer 3

i dont even know how to do it i dont understand it

Answer 4

\[S_n = \frac{n}{2}[2a+(n-1)d]\]
this is the formula you use

Answer 5

oh wow lol can you break that down please

Answer 6

well have you by chance looked at your textbook or something?

Answer 7

the first term is \(a = 1\) and the \(d\) common difference is \(5\)

Answer 8

i dont have a text book i do it online

Answer 9

then you're finding \(S_{12}\)

Answer 10

so what am i doing exactly am i adding or subtracting

Answer 11

\[s_{12} = \frac{12}{2} \left[2(1)+(12-1)*5\right] = ...\]
since n = 12, a = 1 , d = 5; i just subbed it in

Answer 12

would it be 342

Answer 13

well if you got \(342\) then i assume that you're right