a,\(\Delta=3^2-4\left(-2\right).6=9+48=57\)
\(x_1=\dfrac{-3+\sqrt{57}}{-4}=\dfrac{3-\sqrt{57}}{4}\)
\(x_2=\dfrac{-3-\sqrt{57}}{-4}=\dfrac{3+\sqrt{57}}{4}\)
b, \(\Delta=6^2-4.3.3=36-36=0\)
\(\Rightarrow x_1=x_2=\dfrac{-6}{2.3}=\dfrac{-6}{6}=-1\)
c, \(\Delta=1^2-4.6.5=1-120=-119< 0\)
Vậy pt vô nghiệm