Question

The sum of first n terms of an AP is (5n – n²). The nth term of the AP is ______.

Options

• (5 – 2n)

• (6 – 2n)

• (2n – 5)

• (2n – 6)

Answer 1

The sum of first n terms of an AP is (5n – n²). The nth term of the AP is (6 – 2n).

Explanation:

T_n = (S_n – S_{n – 1}) 

= (5n – n²) − {5(n – 1) – (n – 1)²}

= (5n – n²) – (7n – n² – 6)

= (6 – 2n)