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What is the sum of the first 27 terms of the arithmetic sequence? −15,−11,−7,−3...

 Apr 15, 2019

Best Answer 

 #1
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Difference between successive terms = +4

27th term =   a1 + (n-1)(d)

                     -15 + (26)(4) = 89

 

Sn = n (a1+a27)/2 = 27 (-15+89)/2 = 999

 Apr 15, 2019
 #1
avatar+19789 
0
Best Answer

Difference between successive terms = +4

27th term =   a1 + (n-1)(d)

                     -15 + (26)(4) = 89

 

Sn = n (a1+a27)/2 = 27 (-15+89)/2 = 999

ElectricPavlov Apr 15, 2019

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