Help with Math Question from Blue Book

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1

<p>Hey,</p>

<p>Can someone help please explain to me the rules and methods used to solve the math problem on Page 350 of the 2nd Edition Blue Book?</p>

<p>It goes like this:</p>

<p>Graph: <a href="http://imgur.com/40HiP.png%5B/url%5D"&gt;http://imgur.com/40HiP.png&lt;/a&gt;&lt;/p>

<p>The figure above shows the graph y = k - x^2, where k is a constant. If the area of triangle ABC is 64, what is the value of k?</p>

<p>The Blue Book has the answer explanation, but it's not really helping me to understand how its being solved :/</p>

<p>Thanks!</p>

2

<p>Here is my work: <a href=“http://i56.■■■■■■■.com/2h6rct2.png[/url]”>http://i56.■■■■■■■.com/2h6rct2.png&lt;/a&gt;&lt;/p&gt;