deret ke -40 dari barisan bilangan 1,3,5,7
[tex]un = a + (n - 1)b \\ u40 = 1 + (40 - 1)2 \\ u40 = 1 + (39)2 \\ u40 = 1 + 78 \\ u40 = 79[/tex]
sn=n/2(a+un)
S40=40/2(1+79)
S40=20(80)
S40=1600
[answer.2.content][tex]un = a + (n - 1)b \\ u40 = 1 + (40 - 1)2 \\ u40 = 1 + (39)2 \\ u40 = 1 + 78 \\ u40 = 79[/tex]
sn=n/2(a+un)
S40=40/2(1+79)
S40=20(80)
S40=1600
[answer.2.content]