Question

In an A.P., the sum of first n terms is $\frac{3n^2}{2}+\frac{13}{n}n.$ Find its 25^th term.

Answer 1

Here, the sum of first n terms is given by the expression,

We need to find the 25^th term of the A.P.

So we know that the n^thterm of an A.P. is given by,

So …… (1)

So, using the expression given for the sum of n terms, we find the sum of 25 terms (S₂₅) and the sum of 24 terms (S₂₄). We get,

Similarly,

Now, using the above values in (1),

Therefore, .