The sum of first n terms of an A.P. is 5n – n2. Find the nth term of this A.P.
Sn = 5n – n2
First term, a = 5(1) – (1)2
= 5 – 1 = 4
S2 = 5(2) – (2)2
a + (a + d) = 10 – 4
4 + 4 + d = 6
d = -2
Now, the nth term, an = a + (n - 1) d
= 4 + (n – 1) (-2)
= 4 + 2 – 2n = 6 – 2n