Question

Diket daret aritmatika 14+23+32+....+248. tentukan A.a,b dan Un B.n. C.Sn

Answer 1

A).
a=14
b=23-14=9
Un=248
Rumus Un=9n+5

B).
n=(Un-a+b)/b
n=(248-14+9)/9
n=243/9
n=27

C).
Sn=n/2(a+Un)
S27=27/2(14+248)
S27=27/2(262)
S27=27×131
S27=3537