What is the sum of the terms of each finite sequence below?
1) 7,9,11,13,15
2) 2, 6, 10, 14, 18, 22, 26
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1) a= 7 , d= 9-7=2 and n= 5
Sn= n/2{2a+(n-1)d} = 5/2{2×7+(5-1)×2}
Sn = 5/2 {14+4×2}=5/2 {22} = 5×11= 55
Sn= 55
2) a= 2 d= 6-2=4 and n= 7
Sn= n/2{2a+(n-1)d} =7/2{4+6×4} = 7/2×28= 7×14= Sn98
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