mohon bantuannya !!!!

◎ ( 1 ) ◎
Jika :
2 , 4 , 6 , 8

Dari deret trsebut :
b = 2
U1 + U3 = 8
U2 + U4 = 12
→ Berarti U2 + U4 = 8 + 2b


◎ ( 2 ) ◎
Jika :
3 , 6 , 9 , 12

Dari deret tersebut :
b = 3
U1 + U3 = 12
U2 + U4 = 18
→ Berarti U2 + U4 = 12 + 2b


◎ Kembali kesoal ◎

U1 + U3 = 1/x
U2 + U4 = 1/y

U2 + U4 = 1/x + 2b

1/y = 1/x + 2b
1/y = 1/x + 2 (8 - y / 2xy)
1/y = 1/x + (8 - y / xy)
(8 - y / xy) = 1/y - 1/x
(8 - y / xy) = (x - y) / xy
8 - y = x - y
x = 8

◎
U2 + U3 = 3/16
U1 + U3 = 1/8
------------------------- (-)
U2 - U1 = 3/16 - 2/16
U2 - U1 = 1/16
b = 1/16

U1 + U3 = 1/8
U1 = 1/8 - U3
a = 1/8 - (a + 2b)
a = 1/8 - a - 2b
2a = 1/8 - 2(1/16)
2a = 1/8 - (1/8)
a = 0

S32 = n/2 (2a + (n-1)b)
S32 = 32/2 (2a + (32-1)b)
S32 = 16 (2a + 31b)
S32 = 16 (2(0) + 31 (1/16)
S32 = 16 (0 + 31/16)
S32 = 16 (31/16)
S32 = 31