Question

sum of 6 terms in the series 1.2+2.3+3.4+ is

Answer 1

Answer:

The n

th

term =n(n+1)=n

2

+n; and by writing down each term in a similar form we shall have two columns, one consisting of the first n natural numbers, and the other of their squares.

∴ the sum =∑n

2

+∑n

=

6

n(n+1)(2n+1)

+

2

n(n+1)

=

2

n(n+1)

{

3

2n+1

+1}

=

3

n(n+1)(n+2)

.

Answer 2

Answer:

6.9

Step-by-step explanation:

thnks for your question