# Question #e4d1e

##### 2 Answers

You just need to simplify the equation.

Here are the steps, from the beginning to the second line of your problem.

#### Explanation:

You have the following equation:

Note that

so let's say

We get:

This is a quadratic equation that you should know how to solve, using the (in)famous quadratic formula:

where

In our case,

we readily see that we have

So plugging-in these numbers in the quadratic formula gives the following:

so

(Note that this is representing the two solutions of the equation with

Replacing the x back to its original form:

So here we are at the second line. I hope this helped.

We know that the roots of general quadratic equation of the form

Applying this to our quadratic equation of

As

we have

So either

Or