Question

Diketahui suatu barisan aritmatika dengan U9 = 15 dan U17 = 47. Nilai dati U5 adalah..
tolong pakai cara yaa!!

Answer 1

U9 = 15
U17 = 47
b = (47-15)/(17-9)
   = 32/8
   = 4

U9 = U1 + (n-1)b
15 = U1 + (9-1)4
15 = U1 + 32
U1 = -17

U5 = -17 + (5-1)4
U5 = -17 + 16
U5 = -1

Answer 2

U9=a+8b=15
U17=a+16b=47
eliminasi
a+8b=15
a+16b=47
————— kurang
-8b=-32
b=4

a+8b=15
a+8(4)=15
a=15-32
a=-17

u5=-17+4(4)
u5=-17+16
u5=-1