Question

Sum of the arithmetic sequence 8,14,20 if there are 24 terms

Answer 1

1848

Explanation:

a=8

d=14-8=6

n=24

`S_(n)=(n)/(2) [2a+(n-1)d]\\S_(24)=(24)/(2) [2 * 8+(24-1)6]\\=12[16+138]\\=12 * 154\\=1848`

Answer 2

1,848

Explanation:

Find the arithmetic pattern:

*Arithmetic means addition or subtraction*

To get from 8 to 14, we must add 6.

To get from 14 to 20, we must add 6.

The arithmetic pattern is 6.

List the rest of the terms (24 terms total):

8, 14, 20, 26, 32, 38, 44, 50, 56, 62, 68, 74, 80, 86, 92, 98, 104, 110, 116, 122, 128, 134, 140, 146

Formula:

Sn = n (a1 + an/2)

a1 = first term

an = last term

n = number of terms

Sn = 24 (8 + 146/2)

Sn = 24 (154/2)

Sn = 24 (77)

Sn = 1,848