No1.) 1+3+5+7+9+....+99 No2.)1-2-3-4-5-6-7-8+....-100 No3.)-100-99-98-...-2-1-0+1+2+...+48+49+50

1.
A = 1
B = 3 -1 = 2
Banyak suku :
= 99/2
= 49,5 (50)

S50 :
= n/2 (a + Un)
= 50/2 (1 + 99)
= 25 x 100
= 2500

2.
1-2 = -1
3-4 = -1
.. - .. = -1
99-100 = -1

Banyak kali penjumlahan :
= 100/2
= 50

Maka hasilnya :
= 50 x (-1)
= -50

3.
A = -100
B = -99 - (-100) = 1
Banyak suku :
= 100 + 1 + 50
= 151

Jumlah suku :
= n/2 (a + Un)
= 151/2 (-100 + 50)
= 75,5 x (-50)
= -3775