Method of Difference

A sequence is defined by u1 = 1 and u (r+1) = ur + 5r +3 for r = 1,2,3,..

By using method of difference, or otherwise, find uk in terms of k.

Question is why is the upper limit k - 1 and not k?

Hi,

If we use k - 1, we obtain the required expression of u_k directly. Thanks.

Cheers,
Wen Shih