tolong bantuannya malam ini barisan dan deret aritmatika

6. Sn = n^2 - 3 <=> Sn = pn^2 + qn
maka, p = 1/2 b = 1 => b = 2,
dan q = a - 1/2 b = -3
a - 1 = -3 => a = -2

U11 = a + 10b
= -2 + 10.2
= -2 + 20
= 18 (E)