Chapter 9 - Solving Quadratic Equations - 9.5 - Solving Quadratic Equations Using the Quadratic Formula - Exercises - Page 521: 10

$x=\frac{-7\pm \sqrt {-15}}{2}$ The equation has no real solutions.

Comparing $x^{2}+7x+16=0$ with $ax^{2}+bx+c=0$, we get $a=1$, $b=7$ and $c=16$. The quadratic formula is $x=\frac{-b \pm \sqrt {b^{2}-4ac}}{2a}$ Substituting the values, we get $x=\frac{-(7) \pm \sqrt {(7)^{2}-4(1)(16)}}{(2)(1)}=\frac{-7\pm \sqrt {-15}}{2}$ The equation has no real solutions.