The way to solve quadratic inequalities is similar to solve quadratic equation. The first step is to move all the term to one side of the inequality say to the left to get something lik or and then try to factor the left hand side intos something of the form . Now to show that this expression is negative (or positive) we need to do some analysis on where the value of and are positive or negative. To make the analysis easier we use the real line to help us to determine this.

 To make everything clear, you can watch the videos below