5 An arithmetic sequence has first term \(a\) and common difference \(d\). The sum of the first 16 terms of the sequence is 260
5
- Show that \(4 a + 30 d = 65\)
5 - Given that the sum of the first 60 terms is 315 , find the sum of the first 41 terms.
5 - \(\quad S _ { n }\) is the sum of the first \(n\) terms of the sequence.
Explain why the value you found in part (b) is the maximum value of \(S _ { n }\)