Question

Find the sum of the first 8 terms in the geometric sequence: 1, 3, 9, 27,

Answer 1

The sum of the first 8 items in the geometric sequence:1, 3, 9, 27, ...etc is 3280.

Explanation:

The given is,

sequence: 1,3,9,21,.. etc

Step:1

The given is based on multiplication of 3 to previous number,

( x - previous number, next number = 3 ×
`x` )

First term : 1

Second term : 1 × 3 = 3

Third term : 3 × 3 = 9

Fourth term : 9 × 3 =27

Fifth term : 27 × 3 = 81

Sixth term : 81 × 3 = 243

Seventh term : 243 × 3 = 729

Eighth term : 729 × 3 = 2187

Step:2

Sum of first 8 terms
`= 1 + 3 + 9 + 27 + 81 + 243 + 729 + 2187`

= 3280

Sum of first 8 terms = 3280

Result:

The sum of the first 8 items in the geometric sequence:1, 3, 9, 27, ...etc is 3280.