Jerry Gaming : 10:47 15/08/2016
A = 12 - 22 + 32 - 42 +...+ 20152 - 20162
A = 12 - 22 + 32 - 42 +...+ 20152 - 20162
<=> A = (12 - 22) + (32 - 42) +...+ (20152 - 20162)
<=> A = (1 - 2)(1 + 2) + (3 - 4)(3 + 4)+...+ (2015 - 2016)(2015 + 2016)
<=> A = -(1 + 2 + 3 + 4 +...+ 2015 - 2016)
<=> A = -2033136