## Functions Modeling Change: A Preparation for Calculus, 5th Edition

$$z=-2+\sqrt{10},\:z=-2-\sqrt{10}$$
The quadratic formula states: $$x_{1,\:2}=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$$ Thus, solving the equation, we find: $$z_{1,\:2}=\frac{-4\pm \sqrt{4^2-4\cdot \:1\left(-6\right)}}{2\cdot \:1} \\ z=-2+\sqrt{10},\:z=-2-\sqrt{10}$$