Barisan aritmetika memiliki U7=27 dan U11=43, nilai U9= ... . *

Dik. Barisan deret aritmatika : U7 = 27 & U11= 43.
Dit. Suku ke-9 (U9) ?

Jawab...

U11 = a + 10b = 43
U7   = a + 6b    = 27
       ------------------------- (-)
@ 4b = 16
@ b = 4

a :
a + 6b = 27
a + 6(4) = 27
a + 24 = 27
a = 27 - 24
a = 3

U9 = a + 8b
U9 = 3 + 8(4)
U9 = 3 + 32
U9 = 35

Semoga membantu... ^_^