# Chapter 4 - Quadratic Functions and Equations - 4-6 Complete the Square - Practice and Problem-Solving Exercises - Page 237: 28

$81$

#### Work Step by Step

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 $m=18,$ \begin{align*} &=\left(\frac{18}{2}\right)^2\\\\ &=9^2\\\\ &=81 \end{align*}

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