Question

Sum of first n terms of an arithmetic progression a1,a2,a3,......an is:

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

S = ( n / 2 ) [ 2a + ( n - 1 ) d ]  

Step-by-step explanation:

Since we know,

An arithmetic progression is a series of numbers in which each term is derived from the preceding term by adding or subtracting a fixed number called the common difference "d"

For example,  9, 6, 3, 0,-3, .... is an arithmetic progression because we have -3 as the common difference.

The general form of an Arithmetic Progression:

The general form of AP is a, a + d, a + 2d, a + 3d and so on.

Therefore,

nth term of an AP series is $T_{n}$ = a + ( n - 1 ) d,

where  $T_{n}$  = nth term

a = first term

d = common difference

Sum of first n terms of an arithmetic progression a1,a2,a3,......an is

S = ( n / 2 ) [ 2a + ( n - 1 ) d ]