Hello, Tangera!

Here's the first one . . .

The sum of the first terms is: .Q1) An A.P. has terms and common difference , where .Prove that the difference

of the sum of the last terms and the sum of the first terms is:

The last k terms are: .

Their sum is: .

Subtract [2] - [1]: .

. . . . . . . . . . .