Find the sum to n terms of the A.P., whose kth term is 5k+1

1 Answer | Add Yours

Top Answer

justaguide's profile pic

justaguide | College Teacher | (Level 2) Distinguished Educator

Posted on

The sum of n terms of an AP is given by S = n*(T1 + Tn)/2.

Here, the kth term is 1 + 5k.

The first term is T1 = 1 + 5 = 6, the nth term is Tn = 1 + 5n.

Substitute in the expression for S

=> (n/2)(6 + 1 + 5n)

=> (n/2)(7 + 5n)

=> 7n/2 + 5n^2/2

The sum to n terms of the AP whose kth term is 1 + 5k is 7n/2 + 5n^2/2

We’ve answered 318,979 questions. We can answer yours, too.

Ask a question