Question

Find the sum of the summation of 3 i plus2, from i equals 5 to 13.

Answer 1

Have you considered substituting the values given for 'i' and adding them up?

Are you supposed to use the Arithmetic Series sum formula?

Show your work!

Answer 2

Sn=n/2(a1+an)?

Answer 3

I'll take that as a 'yes' to the second question. Okay, how do you interpret the formula, in light of the problem statement?

What is a1?
What is n?
What is an?

Answer 4

a1=17

Answer 5

n=13

Answer 6

an is the number youre looking for

Answer 7

a1 = 3*5 + 2 = 15 + 2 = 17 -- Good.
n = count(5, 6, 7, 8, 9, 10, 11, 12, 13) = 9 -- Whoops!

Answer 8

okay! so thats where i was going wrong

Answer 9

n is the number of terms. Never underestimate the power of simply counting.

Answer 10

is the answer 261?

Answer 11

You tell me.