How do we find excluded values?

Let's say we have an expression that looks something like this -->      -7   
                                                                                                        x-5
Usually we have to find when the value x would satisfy the expression but what about when we have to find the excluded values, what do we do?
Well usually when we have to find the excluded values, the expression will be either in fraction form or in a radical form --> √x-5

There are two rules for finding the excluded values:
1. The denominator CAN'T be ZERO!!
2. Radical can't be negative. 
So first, let's solve the fractional expression!
  -7       First let's take the denominator and make it not equal to zero.
x-5
x-5=0 And then all you have to do is add 5 to both sides.
Your answer should be x=5 so the excluded value is 5!

Now let's take a look at that radical expression! √x-5
We know that the radical cannot be a negative number so in order to find the excluded values we must take out the expression inside the radical and make it less than 0.   x-5<0 
Then you just add five to both sides.
Your final answer should be x<5