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प्रश्न
If the sum of n terms of an A.P. be 3 n2 − n and its common difference is 6, then its first term is
विकल्प
2
3
1
4
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उत्तर
2
\[S_n = 3 n^2 - n\]
\[ \Rightarrow S_1 = 3 \left( 1 \right)^2 - 1\]
\[ \Rightarrow S_1 = 2\]
\[ \therefore a_1 = 2\]
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