Jawabanmu

2014-02-07T21:50:28+07:00
U₁ + U₃ = 3        -----> a + ar² = 3            ----> a(1 + r²) = 3
U₂ + U₄ = 3/2 √2 -----> ar + ar³ = 3/2 √2  -----> ar(1 + r²) = 3/2 √2
pers1 : pers 2
{a(1 + r²)} : {ar(1 + r²)} = 3 : (3/2 √2)                            a dicoret , (1 + r²) dicoret
maka didapat 
1/r = 2/√2
r = √2 / 2 = 0,5√2
a(1 + r) = 3
a(1 + 1/4) = 3
a = 3 : 5/4
a = 12/5