pada suatu barisan geometri naik dengan rasio positif diketahui U6-U4 = 4 dan U4-U3 = 2/3 , maka nilai U5 …., jelaskan

U₆ – U₄ = 4
a r⁵ – a r³ = 4
a r² ( r³ – r) = 4
a r² = 4 / (r³ – r)

U₄ – U₃ = 2/3
a r³ – a r² = 2/3
ar² ( r – 1) = 2/3
a r² = (2/3)/(r – 1)
a r² = 2/ (3(r -1))
2/ (3(r-1)) =  4 / (r³ – r)
2 (r³ – r) = 12 (r -1)
2r (r² -1) = 12 ( r – 1)
2r ( r +1)(r -1) = 12 ( r – 1)
2r (r +1) = 12
r (r +1) = 6
r = 2

U₆ – U₄ = 4
a r⁵ – a r³ = 4
a = 4 / (r⁵ – r³)
a = 4 / (32-8) = 4/24 = 1/6

U5 = a r⁴ = 1/6 ( 2)⁴ = 16/6 = 8/3