Tentukan hasil dari(tanpa menghitung satu persatu) A 1+3+5+7+9+....+99 B 1-2+3-4+5-6+7-8+....-100 C-100-99-98-...-2-1-0+1+2+...+48+49+50

A. S50 = n/2 (2a + (n-1)b)
S50 = 50/2 (2 × 1 + (50-1)2)
S50 = 25 (2 + 49 × 2)
S50 = 25 (2 + 98)
S50 = 25 × 100
S50 = 2500

B. -1 × 50 = -50

C. -50, -49, -48, ..., 48, 49, 50 habis dikurangkan. Jadi yang tersisa hanya -100, -99, ..., -51
Sn = n/2 (2a + (n-1)b)
S50 = 50/2 (2 × (-100) + (50-1)1)
S50 = 25 ((-200) + 49)
S50 = 25 × -151
S50 = (-3.775)