I wonder if you copied something incorrectly, since [imath]kn^2+3n^2[/imath] seems unlikely.the sum of n terms of an arithmetic sequence is kn squared + 3n squared, where k is a real number . show that the first , second and fifth terms of the series are consecutive terms of a geometric sequence. please help me out
@ Dr P No, I think it is correct. It does work out.I wonder if you copied something incorrectly, since [imath]kn^2+3n^2[/imath] seems unlikely.
Please show us an image of the actual problem. Also, tell us what you have learned about the sum of an arithmetic series, so we can start with that.