### Home > CCA > Chapter 9 > Lesson 9.1.2 > Problem9-18

9-18.

Use the Quadratic Formula to solve $x^2−13x+42=0$. Did your solution match the solution from part (a) of problem 9-17?

$\textit{x}=\frac{-\textit{b}\pm\sqrt{\textit{b}^2-4\textit{ac}}}{2\textit{a}}$

Substitute the values from the equation into the formula.

$\textit{x}=\frac{-(-13)\pm\sqrt{(-13)^2-4(1)(42)}}{2(1)}$

Evaluate the equation by using the order of operations.

$\frac{13+\sqrt{1}}{2}\text{ or }\frac{13-\sqrt{1}}{2}$

$x=6\ \text{or}\ 7$; yes