Question

Find the indicated terms in each of the following sequences whose nth terms are

a_n = n (n −1) (n − 2); a₅ and a₈

Answer 1

Here, we are given the n^th term for various sequences. We need to find the indicated terms of the A.P.

a_n = n (n −1) (n − 2)

We need to find `a_5` and `a_8`

Now to `a_5` term we use n = 5 we get

`a_5 = 5(5 -  1)(5 - 2)`

= 5(4)(3)

= 60

Also to find `a_8` term we use n = 8 we get

`a_8 = (8(8 - 1)(8 - 2))`

= 8(7)(6)

= 336

Thus `a_5 = 60 and a_8 = 336`