u2=6 dan u3=9 , u50=?

Dik. barisan deret aritmatika :
U2 = 6 & U3 = 9
Dit. U50 ?

Jawab...

U3 = a + 2b = 9
U2 = a + b = 6
------------------ (-)
@ b = 3

a :
a + b = 6
a + 3 = 6
a = 6-3
a = 3

U50 = a + 49b
U50 = 3 + (49)(3)
U50 = 3 + 147
U50 = 150

Semoga membantu.. ^_^