Answer:
or 
Step-by-step explanation:
We have the following equation:

The first step is to eliminate the square root, it moves to the right side as a power of two:

Now, we develop the right side as a squared binomial:

we put everything together on one side of the equation:

We join like terms:

and we factor the previous equation. For this we will look for two numbers such that:
when multiplying they give us 8, and when they are added they give us 9. those numbers are 8 and 1, since 8*1=8 and 8+1=9.
So the factorization will be as follows:

and the above can have two results, that the first parenthesis is zero, or that the second parenthesis is zero:

or

The answer fot the equation is
or 