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Question
The sum of first n terms of an A.P. is 3n2 + 4n. Find the 25th term of this A.P.
Solution
We know
\[a_n = S_n - S_{n - 1} \]
\[ \therefore a_n = 3 n^2 + 4n - 3 \left( n - 1 \right)^2 - 4\left( n - 1 \right)\]
\[ \Rightarrow a_n = 6n + 1\]
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