Find the rth term of the AP, the sum of whose first n terms is (3n2 +

1.	Find the rth term of the AP, the sum of whose first n terms is (3n2 + 2n).
Answer» Given: The sum of first n terms. To Find: The r^th term. Let the first term be a and common difference be d Put n = 1 to get the first term a = S₁= 3 + 2 = 5 Put n = 2 to get a + (a + d)2a + d = 12 + 4 = 1610 + d = 16d = 6t_r = a + (r - 1)d t_r = 5 + (r - 1)6 = 5 + 6r - 6 = 6r - 1 The r^th term is given by 6r - 1.

Find the rth term of the AP, the sum of whose first n terms is (3n2 + 2n).

Answer»

Given: The sum of first n terms.

To Find: The r^th term.

Let the first term be a and common difference be d

Put n = 1 to get the first term

a = S₁= 3 + 2 = 5

Put n = 2 to get a + (a + d)2a + d = 12 + 4 = 1610 + d = 16d = 6t_r = a + (r - 1)d t_r = 5 + (r - 1)6 = 5 + 6r - 6 = 6r - 1

The r^th term is given by 6r - 1.