Question

Sum of forst 30 terms whose nth term is 3-2n

Answer 1

answer:

It is given that the th term of A.P is .

We know that the general term of an arithmetic progression with first term and common difference is , therefore,

Comparing the above term by the general term of A.P, we get and

We also know that the sum of an arithmetic series with first term and common difference is

Now to find the sum of first terms of an A.P, substitute and in as follows:

Hence, the sum of first terms is 30 and 1020