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gumball4585
your answer if you are in algebra 2 and you have this on online school would be -2,109

The sum of the given series is -2664.

We have given the series,

15 + 11 + 7 + . . . + (–129)

by using the Gauss's method

What is the value of n?

[tex](first term-last term)/d+1=n[/tex]

Total number of terms in the given series are

[15-(-129)]/4+1=36+1=37

S=15+11+7+....-125-129

S=-129-125-...+7+11+15

--------------------------------

2S=-114-114-114...(37 times)

[tex]sum=2S= (-114)\times 37\\2S=-5328[/tex]

Divide by 2

[tex]sum=S=1/2\times (-114)\times 37\\S=-2664[/tex]

Therefore the sum of the given series is -2664.

To learn more about the sum of the series visit:

https://brainly.com/question/24205483

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