The sum of the first five terms of the geometric sequence is -1555
Sum of geometric sequence
The formula for calculating the sum of geometric sequence is expressed as:
[tex]S_n=\frac{a(r^n-1)}{r-1}[/tex]
where
r is the common ratio = 6/1 = 6
a is the first term = -1
n = 5 (number of terms)
Substitute
[tex]S_5=\frac{-1(6^5-1)}{6-1}\\S_5=\frac{-7776+1}{5}\\S_5=-1555[/tex]
Hence the sum of the first five terms of the geometric sequence is -1555
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