Nomor 45 dongs :). Saya ga ketemu temu akar akarnya

3x^2 - 12x + 21 = 0

p^2 + q^2 + 7pq
= p^2 + 2pq + q^2 + (5pq)
= (p + q )^2 + 5pq

p + q = -b/a
= - (-12)/3 = 4

pq = c/a
= 21/3 = 7

-->
4^2 + 5(7)
16 + 35
= 51

C