[tex]9x^2-17x-85=0\\\\\Rightarrow\ \ \ \Delta=(-17)^2-4\cdot9\cdot(-85)=289+3060=3349\\\\\Delta>0\ \ \ \Rightarrow\ \ \ two\ real\ solution:\\\\x_1= \frac{\big{17- \sqrt{3349} }}{\big{2\cdot9}} =-2.27058584361...\approx-2.271\\\\x_2= \frac{\big{17+ \sqrt{3349} }}{\big{2\cdot9}} =4.1594747325...\approx4.159[/tex]
