Which value of k will make x^2-1/4x+k a perfect square trinomial?

For this case we have the following polynomial:
 
 We suppose that we have a standard equation of the form:
 
 To make a perfect square trinomial, we need to complete the square.
 Therefore, the value of c is:
 
 Using this definition for this case, we have:
 
 
 
 Therefore, the perfect square trinomial is:
 
 
 The value of k is:
 

9/12 is the answer because 3/4 times 3 each is 9/12