(a) tentukan nilai x (b) hitung jumlah delapan suku berikutnya

Pada barisan aritmatika, beda = b = U2-U1 = U3-U2 U1 = x+1 U2 = 2x-1 U3 = 2x+2 (a) U2-U1 = U3-U2 2x-1 - (x+1) = 2x+2 - (2x-1) 2x-1-x-1 = 2x+2-2x+1 x-2 = 3 x = 3+2 x = 5 U1 = a = x+1 = 5+1 = 6 U2 = 2x-1 = 2.5 - 1 = 10-1 = 9 U3 = 2x+2 = 2.5 + 2 = 10+2 = 12 Beda = b = U2-U1 = 9-6 = 3 U11 = a + 10b = 6 + 10.3 = 36 (b) Jumlah 8 suku berikutnya = S11 - S3 S3 = 6+9+12 = 27 S11 = (11/2) x (a + U11) = (11/2) x (6+36) = (11/2) x 42 = 11 x 21 = 231 Jumlah 8 suku berikutnya = S11-S3 = 231-27 = 204