Use this rule on the left side:
               

, 

Now use this rule to rewrite the equation:
                is equivalent to 

, 

Simplify, FOIL out the right side:

,  

, 

Get  on the left by subtracting
7 from both sides:

, 

, 

Factor the right side:

, 
             
Use the zero-factor principle:

x-3=0 gives x=3
x+5=0 gives x=-5

However we must discard that second answer
because we are given the restriction that 

So the only solution is 

Edwin