Question

For an A.P. ,The first two term are -3, 4. The 21st term is

Answer 1

The 21st term is 137.

Explanation:

Arithmetic progression:

In an arithmetic progression the difference between consecutive terms is always the same, and its called common difference.

The nth term is given by:

`a_n = a_1 + (n-1)d`

In which
`a_1` is the first term and d is the common difference.

The first two terms are -3, 4.

This means that
`a_1 = -3, d = 4 - (-3) = 7`

So

`a_n = a_1 + (n-1)d`

`a_n = -3 + 7(n-1)`

The 21st term is

`a_(21) = -3 + 7(21-1) = -3 + 140 = 137`

The 21st term is 137.