bila a=1/8, dan r=1/2, hitunglah U10 dan S10

Diketahui :
a = 1/8
r = 1/2

Ditanya :
U10
S10

Dijawab :
Un = a.[tex]r^{n-1} [/tex]

U10 = [tex] \frac{1}{8} [/tex]×[tex] \frac{1}{2} ^{9} [/tex]
U10 = [tex] \frac{1}{4096} [/tex]

Karena r = 1/2, r < 1, maka :
Sn = [tex] \frac{a(1-r^n)}{1-r} [/tex]

S10 = [tex] \frac{ \frac{1}{8}(1- \frac{1}{2} ^{10}) }{1- \frac{1}{2} } \\ \\ = \frac{ \frac{1}{8}(1- \frac{1}{1024}) }{ \frac{1}{2}} \\ \\ = \frac{1}{4} (1- \frac{1}{1024}) \\ \\ = \frac{1}{4} ( \frac{1023}{1024} ) \\ \\ = \frac{1023}{4096} [/tex]