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Dovator [93]
3 years ago
9

Find S15 for the series -1 + -3 + -5 + -7 +...

Mathematics
1 answer:
Ber [7]3 years ago
8 0
Hello :
the sum is  arithmetic secquence of common -diff is :
(-7)-(-5) =(-5)-(-3) = (-3)-(-1) =-2 = d
  the first term is : a1 = -1
<span>the formula of the sum :  S= (n/2)(a1 +an)
n is number of term       an = a1+(n-1)d</span>
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Answer:

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Step-by-step explanation:

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