SOLUTION: Write each series as a summation in sigma notation. 10+20+40+80

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Question 1151137: Write each series as a summation in sigma notation.
10+20+40+80
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

Answer:

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More explanation:

If you plugged in k = 1, you'd get as the first term.
If you plugged in k = 2, you'd get as the second term.
If you plugged in k = 3, you'd get as the third term.
If you plugged in k = 4, you'd get as the fourth term.

So,

The sequence 10, 20, 40, 80, ... is geometric with
a = first term = 10
r = common ratio = 2
The general nth term of a geometric sequence is