\(\sum_{n=1}^{15} (2n-1)\)
First term = 2(1) - 1 = 1
15th term = 2(15) - 1 = 29
Sum = [ first term +last term ] * number of terms / 2 =
[ 1 + 29 ] * 15 / 2 =
[30] * 15 / 2 =
450 / 2 =
225
