Question

Sum to n terms 1.(3n–1) + 2. (3n–2) + 3.(3n–3) + .............n terms is

(a) \(\frac{n(2n + 1)(5n -1)}3\)

(b) \(\frac{n(2n + 1)(5n +1)}3\)

(c) \(\frac{n(n + 1)(7n -1)}6\)

(d) None of these.

Answer 1

Correct option is (c) \(\frac{n(n + 1)(7n -1)}6\)