Chapter 8 - Section 8.2 - Solving Quadratic Equations by the Quadratic Formula - Exercise Set - Page 492: 6

-5

Using $\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}$ (or the Quadratic Formula), the solutions of the given quadratic equation, $ y^2+10y+25=0 ,$ are \begin{array}{l}\require{cancel} \dfrac{-(10)\pm\sqrt{(10)^2-4(1)(25)}}{2(1)} \\\\= \dfrac{-10\pm\sqrt{100-100}}{2} \\\\= \dfrac{-10\pm\sqrt{0}}{2} \\\\= \dfrac{-10}{2} \\\\= -5 .\end{array}