The sum of the first 8 items in the geometric sequence:1, 3, 9, 27, ...etc is 3280.
Step-by-step 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 × )
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
= 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.