If a1 + a2 + a3 + … + an = 3(2n+1 – 2), for every n ≥ 1, then a11 equals
Explanation:
Eleventh term of the series (a11) = S11 − S10 (where Sn represents the sum of n terms of the series)
S11 = 3(212 − 2) and S10 = 3(211 − 2).
∴ a11 = 3(212 − 2) - 3(211 - 2) = 3(212 − 211) = 3 × 211 (2 − 1) = 6144.
Hence, 6144.
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