Verified Answer :

1/64, because (-1/4)/2 is -1/8, and -1/8  ^2 is 1/64

For this case we have the following polynomial:
 \(x^2 - \frac{1}{4}x + k\)
 We suppose that we have a standard equation of the form:
 \(ax ^ 2 + bx + c\)
 To make a perfect square trinomial, we need to complete the square.
 Therefore, the value of c is:
 \(c = (\frac{b}{2})^2\)
 Using this definition for this case, we have:
 \(k = (\frac{\frac{-1}{4}}{2})^2\)
 \(k= ( \frac{-1}{8} )^2\)
 \(k = \frac{1}{64}\)
 Therefore, the perfect square trinomial is:
 \(x^2 - \frac{1}{4}x + \frac{1}{64}\)
 Answer:
 
The value of k is:
 
\(k = \frac{1}{64}\)