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

Guest Apr 15, 2019

#1**+1 **

Difference between successive terms = +4

27th term = a1 + (n-1)(d)

-15 + (26)(4) = 89

Sn_{ }= n (a_{1}+a_{27})/2 = 27 (-15+89)/2 = 999

ElectricPavlov Apr 15, 2019

#1**+1 **

Best Answer

Difference between successive terms = +4

27th term = a1 + (n-1)(d)

-15 + (26)(4) = 89

Sn_{ }= n (a_{1}+a_{27})/2 = 27 (-15+89)/2 = 999

ElectricPavlov Apr 15, 2019