Question

what will be 50th term of the series having generalised fourmla (8x+5)​

Answer 1

On inspection we see that:

The 2nd term is the 1st term incremented by 4 or 1+3.

The 3rd term is the 2nd term incremented by 7 or 1+3+3

The 4th term is the 3rd term incremented by 10 or 1+3+3+3

The 5th term is the 4th term incremented by 13 or 1+3+3+3+3

So, for every nth term we can assume it to be the (n-1)th term + 1 + (n-1)*3

We can see then that any nth term is 1+(1+3)+(1+3+3)+(1+3+3+3)+…..

= n + 3+6+9+18+…… = n+3(1+2+3+….(n-1))

For the 50th term the value would be 50+3(1+2+3+….+49)

The sum of all positive integers from 1 to m is m(m+1)/2. Here m is 49.

Therefore the 50th term is then 50+3(49*50)/2 = 3725

Answer 2

Answer:

The 50th term is 3725 .

Hope it will help you