Bagaimana cara menghitung bilangan -100-99-98-...-2-1-0+1+2+...+97+98+99

Materi : Barisan dan deret
Kelas : VIII

a=-100
b=u2-u1=-99-(-100)=1

Un=a+(n-1)b
99=-100 + (n-1)1
199 = n-1
n=200

S200 = n/2(2a+(n-1)b)
S200 = 200/2(2.-100 + (200-1)1)
S200 = 100 (-200 + 199)
S200 = 100 (-1)
S200 = -100

= (-100 + 99) + (-99 + 98) + (-98+97)... +(-1 +0)
= -1 x 100
= - 100