Question

What is the sum of the arithmetic sequence 3, 11, 19 ..., if there are 26 terms?

Answer 1

common difference is 8

Answer 2

first term is 3

Answer 3

3x + 8x (x - 1)/2

x = the number of terms so 26.

Answer 4

there are a few ways to approach this, either way you have to determine the a1 + d(n-1) setup

the 26th term is of course: 3 + 8(25)

26 [3+3+8(25)]
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2

Answer 5

26 terms

first = 3
last = 3+8(25)

first + last = 3+3+8(25) = 206

26(206) = 5356

and half of that is ....

Answer 6

2,678!
Thank You! :)

Answer 7

it gets easier with practice :) your welcome