Question

U4=7 ,U6+U8=23 .BESAR U 20

Answer 1

U4 = 7
u5 = 8,5
u6 = 10
u7 = 11,5
u8 = 13
u 20 = 7+{(20-4)*1,5)}
         = 7+24
         = 31

Answer 2

U₄ = a + 3b = 7 ... (1)
U₆ + U₈ = (a + 5b) + (a + 7b)
            = 2a + 12b = 23 ... (2)

(1) x 2 -> 2a + 6b = 14
(2) - (1) -> 6b = 9
                 b = 1.5, a = 3.5

U₂₀ = a + 19b
      = 3.5 + 28.5
      = 32


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