General Series

1. To find the sum of first n natural numbers.

or

Suggested answer:

Let S_n = 1+2+3+4+...+n

This series is an A.P.

Here a=1, d=1, l = t_n = n

2. To find the sum to squares of first n natural numbers.

or

Suggested answer:

. . . .

. . . .

. . . .

Adding vertically,

3. To find the sum to the cubes of first n natural numbers.

or

Suggested answer:

Adding vertically,

4. Method of finding sum of a series whose n^th term is known.

Suggested answer:

Let the n^th term of series be an³ + bn² + cn + d

t_n = an³ + bn² + cn + d where a, b, c, d are constants.