Chapter 4 Quadratic Functions and Factoring - 4.8 Use the Quadratic Formula and the Discriminant - 4.8 Exercises - Skill Practice - Page 296: 43

$$x=5/14, -2.5$$

When given the choice to use any method, the quadratic formula is a good choice because it will always work. We first check that the function is in the form $ax^2+bx+c$. Then, using the quadratic formula, we obtain: $$x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$$ $$x=\frac{-60\pm \sqrt{(60)^2-4(28)(-25)}}{2(28)}$$ $$x=5/14, -2.5$$