Taking the square root of both sides gives two possible cases,
or
Recall that
If and
, we have
so in the equations above, we can write
Then in the first case,
(where is any integer)
and in the second,
Then the solutions that fall in the interval are
We have .
First let us factor the 2 to obtain,
We can now see clearly that the expression inside the parentheses is a difference of two squares.
We now write the 4 as 2². So that we obtain the expression,
Recall that
Hence our expression becomes,
Therefore, when factored completely,
