Answer:
-56/9
Step-by-step explanation:
By Vieta's formulas,
$r + s = -\frac{4}{3}$ and $rs = \frac{12}{3} = 4.$ Squaring the equation $r + s = -\frac{4}{3},$ we get
$r^2 + 2rs + s^2 = \frac{16}{9}.$ Therefore,
$r^2 + s^2 = \frac{16}{9} - 2rs = \frac{16}{9} - 2 \cdot 4 = -\frac{56}{9}}$
