Question

1.) Use sigma notation to describe the sum of the first ten terms of the arithmetic sequence.
20+18.5+17+15.5+14+12.5+11+9.5+8+6.5

2.)Use sigma notation to describe the sum of the first ten terms of the geometric sequence.
(40)+(-10)+(5/2)+(-5/8)+(5/32)+(-5/126)+(5/512)+(-5/2046)+(5/8192)+(-5/32768)

Answer 1

9
∑ 20-1.5n
n=0

9
∑ 40(-1/4)^n
n=0