Hitunglah jumlah 100 suku pertama deret a. 1+3+5..... b. 13+8+3.....

a. 1 + 3 + 5
barisan aritmatika
a = 1
b = 2
S100 = n/2 (2a+(n-1)b)
= 100/2 (2+(99)2)
= 50 (198+2)
= 50 (200)
= 10.000

b 13 + 8 + 3
barisan aritmatika
a = 13
b = -5

S100 = n/2 (2a+(n-1)b)
= 100/2 (26 + (99)-5)
= 50 (26-495)
= 50 (-469)
= -23450