Suatu barisan arimetika mempunyai u5=-6 dan u2+u10=-16 suku ke 31 adalah? Pakai caranya ya(:

Materi : Barisan dan deret

Pembabasan :
U2 + U10 = -16
a + b + a + 9b = -16
2a + 10b = -16
a + 5b = -8
a + 4b + b = -8
-6 + b = -8
Beda = -2

Maka...
U31 = a + 30b
U31 = a + 4b + 26b
U31 = -6 + 26(-2)
U31 = -6 - 52
U31 = -58

Bab Barisan dan Deret
Matematika SMP Kelas VIII

U2 + U10 = -16
a + b + a + 9b = -16
2a + 10b = -16
a + 5b = -8

U5 = a + 4b = -6

a + 5b = -8
a + 4b = -6
---------------- -
       b = -2

U31 = U5 + 26 x b 
        = -6 + 26 x (-2)
        = -6 - 52
        = -58