SOLUTION: Write the series using summation notation. 15 + 1 + (-13) + (-27)

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Question 292655: Write the series using summation notation.
15 + 1 + (-13) + (-27)
Answer by Edwin McCravy(20056) About Me  (Show Source):
You can put this solution on YOUR website!
15 + 1 + (-13) + (-27)

a%5B2%5D-a%5B1%5D=%281%29-%2815%29=-14
a%5B3%5D-a%5B2%5D=%28-13%29-%281%29=-14
a%5B4%5D-a%5B3%5D=%28-27%29-%28-13%29=-27%2B13=-14

So this is a 4-term arithmetic series with d=-14.

a%5Bn%5D=a%5B1%5D%2B%28n-1%29d
a%5Bn%5D=15%2B%28n-1%29%28-14%29
a%5Bn%5D=15-14%28n-1%29
a%5Bn%5D=15-14n%2B14
a%5Bn%5D=29-14n

sum%28a%5Bn%5D%2Cn=1%2C4%29=sum%28%2829-14n%29%2Cn=1%2C4%29

Edwin