1/2 / 4
which can be rewritten as 1/2 * 1/4 (i bet you learnt how to divide fractions ... if you didnt then comment and ill tell you the rules for dividing) 
1/2 * 1/4 = 1/8
 
        
             
        
        
        
Let's take a look at a perfect square trinomial.

We can distribute this expression to get 

.
An important relation to recognize here is that the constant is the square of half of the x value.
Now, if we wanted to add a number to 

 to make a perfect square trinomial, we could have the value of x and then square it.
Half of 16 is 8, and 8 squared is 
 
 
        
        
        
He only puts 1 in each glass and he has six. The answer is 6.
        
                    
             
        
        
        
Answer: I believe the answer is the second choice.  
81y^4 - 16x^2, the difference of squares.
Step-by-step explanation: