Question

Find the sum of the series 1.2.5 +2.3.6 +3.4.7 +........... To n terms?

Answer 1

Answer:

Step-by-step explanation:

Tn= n (n+1) (n+4)

Let Sn be the sum of n terms of the sequence.

S={n^2(n+1)^2}÷4 +{5n(n+1) (2n+1)}÷6 +{4(n) (n+1)}÷2

n(n+1) {[3n^2+3n+20n+10+24]÷12}

(n(n+1) ÷12) [3n^2+23n+34] ANS