……………..Soal di foto

2017² – 2016² + 2015² – 2014² + 2013² – 2012² + … + 3² – 2² + 1² – 0²

a² – b² = (a + b) (a – b)

2017² – 2016² = (2017 + 2016) (2017 – 2016)

= 4033

2015² – 2014² = 4029

2013² – 2012² = 4025

4033, 4029, 4025, …..

selisih 4 angka

maka Sn = n/2(2a + (n – 1)b)

n = 2018/2 = 1009

a = 4033

b = -4

S1009 = 1009/2(2.4033 + (1009 – 1)(-4))

= 1009/2(8066 – 4032)

= 1009/2 (4034)

= 2.035.153