In the arithmetic sequence, when A1 is greater than 0.s9 = S17 and N is equal to, Sn has the maximum value/

In the arithmetic sequence, when A1 is greater than 0.s9 = S17 and N is equal to, Sn has the maximum value/

The simplest method is n = (9 + 17) / 2 = 13
The reasoning is complicated