Series

Your task is express the sum of the following arithmetic series for n = 14:

S(n) = 11 + 13 + 15 + 17 + ... + 2n+9 + 2n+11

Result

S =  336

Solution:

a1=11 d=2 an=11+2(n−1)  S14=14⋅a1+a142=14⋅11+372=336a_1 = 11 \ \\ d = 2 \ \\ a_n = 11 + 2(n-1) \ \\ \ \\ S_{ 14 } = 14 \cdot \dfrac{ a_1 + a_{ 14}}{2} = 14 \cdot \dfrac{ 11 + 37 }{2} = 336

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