Question

Deret aritmatika, u6=17 u10=33,jml 30 suku pertama deret?

Answer 1

U10=a+9b=33
U 6 =a+5b=17
---------------------- -
4b=16
b=16/4
b=4

a+5b=17
a+5.4=17
a=17-20
a=-3

Sn=½n(2a+b(n-1))
S30=½.30(2(-3)+4.29)
S30=15(110)
S30=1650