Question

diket barisan geometri
u3=18
u7=1458
tentukan: a.rasio?
b.suku ke-1?
c.jumlah 6 suku ​

Answer 1

Penjelasan dengan langkah-langkah:

U3 = 18

U7 = 1.458

a. rasio =...

b. a =...

c. S6 =...

[tex] \frac{a \times r {}^{2} }{a \times r {}^{6} } = \frac{18}{1.458} \\ \frac{r {}^{2} }{r {}^{6} } = \frac{1}{81} \\ r {}^{ - 4} = \frac{1}{81} \\ r {}^{ - 4} = 3 {}^{- 4} \\ r = 3[/tex]

[tex]a \times r {}^{2} = 18 \\a \times 3 {}^{2} = 18 \\ a \times 9 = 18 \\ a = 2[/tex]

S6 =

[tex] \frac{a(r {}^{n} - 1) }{r - 1 \\ } \\ \frac{2(3 {}^{6} - 1) }{2} \\ \frac{2(728)}{2} \\ = 728[/tex]