tentukan penjumlahan dari 2+4+6+8+...60=

a = 2
b = 2
Un = a + (n-1)b
60 = 2 + (n-1)2
60=2+2n-2
2n= 60
n=30
Sn = n/2 (2a + (n-1)b)
= 30/2 ( 2(2)+(30-1)2)
= 30(2 + 29)
= 30(31)
= 930

Sn = n/2(2a+(n-1)b)
S60 = 60/2 (2.2+(59)2)
S60 = 30(4+59.2)
S60 = 30(4+118)
S60 = 30(122)
S60 = 3660