Q23 of 47 Page 1

Find the sum of first 24 terms of an A.P. whose nth term is given by an = 3 + 2n.

Given:

an = 3 + 2n


The First Term of the A.P. a1 is


a1 = 3 + 2 × 1


⇒ a1 = 5


The 24th term of the A.P. a24 is


a24 = 3 + 2 × 24


⇒ a24 = 51


Therefore The First 24 terms of the A.P. = 0.5 × n(a1 + a24)


⇒ Sum of the series = 0.5 × 24(5 + 51)


⇒ Sum of The Series = 0.5 × 24 × 56


Answer: Sum of the series = 672


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