Question

The sum of first n terms of an AP is 4n-n2 what is the first term

Answer 1

$sum \: of \: ap = \frac{n}{2} (2a + (n - 1)d) \\ = > 4n - {n}^{2} = n(4 - n) = \frac{n}{2} (2a + (n - 1)d) \\ \\ = > 4 - n = 2a + (n - 1)d$
Now by further simplification u can get the value of "a" which is first term.
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