Question

Jika jumlah deret tak hingga 2/3 a + a² + 3/2 a³ + .. sama dengan 2 maka nilai a adalah..
a. 4/11
b. 5/11
c. 6/11
d. 7/11
e. 8/11

Answer 1

U1  = 2/3 a
r = 3/2 a
s~ = U1/(1-r)
2 = (2/3 a)/ ( 1 - (3/2 a))
2/3  a = 2( 1- 3/2 a)
2/3 a = 2 - 3a
2a = 6 - 9a
11 a  = 6
a = 6/11