078ddd90-db9c-45e5-909d-3a3f64da5c37.html

<h3>Cool Down (5 minutes)</h3>
<h4>Student Activity</h4>
<ol class="os-raise-noindent">
  <li>Explain why it makes sense to call the expression \(x^2+20x+100\) a perfect square.</li>
</ol>
<p>Write down your answer, then select the <strong>solution</strong> button to compare your work.</p>
<p><strong>Answer:</strong> It is equivalent to \((x+10)^2\), so it is a factor squared.</p>
<ol class="os-raise-noindent" start="2">
  <li>Solve \(x^2+20x+100=81\).</li>
</ol>
<p><strong>Answer: </strong> \(x = -1\) and \(x = -19\)</p>
<h4>Response to Student Thinking</h4>
<h5>More Chances</h5>
<p>If students solve the second equation by factoring and using the square root property, state that some equations cannot be easily factored and that Lessons 9.2-9.4 explore equations that cannot always be easily factored but can be solved by completing the square.</p>