Chapter 4 - Quadratic Functions and Equations - 4-6 Complete the Square - Practice and Problem-Solving Exercises - Page 237: 30

$144$

RECALL: To complete the square for $x^2 +mb$, just add $\left(\dfrac{m}{2}\right)^2$. Using the rule above, the term that must be added to the given expression to complete the square is: With $m=-24$ \begin{align*} &=\left(\frac{-24}{2}\right)^2\\\\ &=\left(-12\right)^2\\\\ &=144 \end{align*}