2:
a: \(A=\dfrac{x_1+x_2}{x_1x_2}=\dfrac{-6}{3}=-2\)
b: \(B=\dfrac{\left(x_1+x_2\right)^2-3x_1x_2}{1-x_1x_2}=\dfrac{36-3\cdot3}{1-3}=\dfrac{36-9}{-2}=-\dfrac{27}{2}\)
c: \(C=\sqrt{\left(x_1+x_2\right)^2-4x_1x_2}\)
\(=\sqrt{\left(-6\right)^2-4\cdot3}=2\sqrt{6}\)
d: \(D=\left(x_1+x_2\right)^3-3x_1x_2\left(x_1+x_2\right)-3x_1x_2\)
\(=\left(-6\right)^3-3\cdot3\cdot\left(-6\right)-3\cdot3\)
=261