Jawabanmu

2014-02-13T17:39:56+07:00
a. 2+5+8+11+...


a=2, b=3, n=20


S20=1/2 (20) (2.2+(20-1)3)= 10 (4+(19)3)=10 (4+57)=10 (61) = 610

MASIH Q JAWABANNY BUKAN GTU , uuu nambah bingung
gmn?
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hadeuuuuuuhhh
hheheheh....
2014-02-13T17:59:56+07:00
C.a=6    b=5
un=a+(n-1)b
101=6+(n-1)5
101-6=5n-5
100=5n          n=20
S20=n/2(a+un)
=20/2(6+101)
=10(107)=1070

bener ga bro?