College Algebra (10th Edition)

$\dfrac{25}{4}$
RECALL: To complete the square for $x^2+bx$, $(\frac{b}{2})^2$ must be added. The given expression has $b=-5$. Thus, to complete the square, add $(\frac{-5}{2})^2=\frac{25}{4}$. Therefore, the missing expression in the given statement is: $\dfrac{25}{4}$