mohon kak soal no 16 beserta caranya.

3x^2 + 5x + 1 = 0
A + B = -5/3
AB = 1/3
1/A^2 + 1/B^2= ( A^2 + B^2) /( A^2.B^2)
= { (A + B)^2 -2AB } / (AB)^2
= { (-5/3)^2 -2(1/3) } / (1/3)^2
= (25/9 -2/3)/ 1/9
= (19/9)/(1/9)
= 19