To solve a quadratic equation means to find all the roots of the quadratic equations.

Example:
Find the roots of the quadratic equations
a. ${x}^{2}=9$
b. $2{x}^{2}-98=0$

(a)
$\begin{array}{l}{x}^{2}=9\\ x=±\sqrt{9}\\ x=±3\end{array}$

(b)
$\begin{array}{l}2{x}^{2}-98=0\\ 2{x}^{2}=98\\ {x}^{2}=\frac{98}{2}=49\\ x=±\sqrt{49}=±7\end{array}$

A quadratic equation may be solve by using one of the following method
1. Factorisation
2. Completing the square