What is the sum of the arithmetic sequence 8, 14, 20 ..., if there are 24 terms?

The answer is 1848

Sum of arithmetic sequence:

s = n (a1 + an) / 2

n - number of terms

a1 - the first therm

an - n-th term

an = a1 + (n - 1) d

d - common difference

n = 24

a1 = 8

d = 6 (14 - 8 = 6; 20 - 14 = 6)

an = 8 + (24 - 1) * 6 = 8 + 23 * 6 = 146

s = n (a1 + an) / 2

s = 24 * (8 + 146) / 2

= 24 * 154 / 2

= 1848

The sum is 6. An=8plus6 (n-1)