suku 4 barisan aritmatika =110 sedang suku 9 =150 maka suku ke 30

b = 150-110 / 9-4=40/5=8

a = U4 - 3b
= 110-3(8)
=110-24
= 86

U30= a + 29b
= 86 + 29(8)
= 86 + 232
= 318

u4 = a + 3b = 110
u9 = a + 8b = 150
-------------------------- -
- 5b = - 40
b = 8

a + 3b = 110
a + 24 = 110
a = 86

Un = a + (n-1) b
u30 = 86 + 29(8)
u30 = 86 + 232
u30 = 318

✔ senang bisa membantu, semoga bermanfaat ya :)