Tentuka rasio,suku pertama dan suku ke 12 dari barisan geometri berikut: A)4,2,1,1/2 B)5,10,20

a) 4,2,1,[tex] \frac{1}{2} [/tex]
r = [tex] \frac{ U_{2[tex]{ U_{1} } [/tex]
r = [tex] \frac{1}{2} [/tex]

[tex] U_{1} = a = 4[/tex]

[tex] U_{n} = a. r^{n-1} \\U_{11} = a.r ^{11} \\ U_{11} = 4 ( \frac{1}{2} )^{11} \\U_{11} = \frac{1}{512} [/tex]

b) 5,10,20
[tex]r= \frac{U_{2}}{U_{1}} [/tex]
[tex]r= \frac{10}{5} \\r=2 \\ \\ U_{1}=a=5 \\ \\ U_{12} = a.r^{11} U_{12} = 5 (2)^{11} U_{12} = 10240[/tex]