Question

Show that 9x^2-17x-85=0 give you solutions to 3 correct significant figures

There are two possible answers for x

Answer 1

`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- √(3349) }}{\big{2\cdot9}} =-2.27058584361...\approx-2.271\\\\x_2= \frac{\big{17+ √(3349) }}{\big{2\cdot9}} =4.1594747325...\approx4.159`