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Find the sum of the first $28$ terms of an A.P. whose $n^{th}$ term is given by $a_n = 3n – 2$.
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Sol. $a_1 = 3 (1) - 2 = 1$ (1/2 Mark)
and $a_{28} = 3 (28) - 2 = 82$ (1/2 Mark)
S$_{28} = \frac{28}{2} \times (1+82)$ (1/2 Mark)
$= 1162$ (1/2 Mark)
and $a_{28} = 3 (28) - 2 = 82$ (1/2 Mark)
S$_{28} = \frac{28}{2} \times (1+82)$ (1/2 Mark)
$= 1162$ (1/2 Mark)