Jika S5=5.000 S9=0 hitunglah S1 b dan S6
Jawaban Terkonfirmasi
S9 = 9/2 x (2a + 8b )
0 = 9(a + 4b)
9a + 36b = 0
S5 = 5/2 x (2a + 4b)
5.000 = 5(a + 2b)
a + 2b = 5.000/5
a = 1000 – 2b
9(1000 – 2b) + 36b = 0
36b – 18b = -9000
18b = -9000
b = -9000/18
b = -500
a = 1.000 – 2x(-500) = 2.000
S6 = 6/2 x (2×2000 – 500×5)
S6 = 3 x (4000-2500)
S6 = 3 x 1.500
S6 = 4.500
cara lain :
S6 = S5 + b = 5.000 – 500 = 4.500