Jika suku perama suatu barisan geometri=16 dan suku ketiga=36,maka besarnya suku kelima adalah?

a = 16
[tex]un = a {r}^{n - 1} \\ u3 = 16 {r}^{3 - 1} \\ 36 = 16 {r}^{2} \\ \frac{36}{16} = {r}^{2} \\ r = \sqrt{ \frac{36}{16} } = \frac{9}{4} = \frac{3}{2} \\ \\ u5 = a {r}^{4} \\ u5 = 16 \times ( { \frac{3}{2}) }^{4} \\ = 16 \times \frac{81}{16} = 81[/tex]