Question

Find the sum to n terms of the series 1 × 2 × 3 + 2 × 3 × 4 + 3 × 4 × 5 + …

Answer 1

The given series is 1 × 2 × 3 + 2 × 3 × 4 + 3 × 4 × 5 + …

n^th term, a_n = n ( n + 1) ( n + 2)

= (n² + n) (n + 2)

= n³ + 3n² + 2n