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Marina solved the quadratic equation 9x^2 - 36x - 720 = 0 by completing the square. In the process, she came up with the equivalent equation
(x + r)^2 = s
where r and s are constants. What is s?

 Jun 17, 2022
 #1
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Divide by 9: \(x^2 - 4x - 80 = 0 \)

 

Complete the square on the left: \((x-2)^2 - 84 = 0 \)

 

Add 84 to both sides: \((x-2)^2 = 84\)

 

So, \(s = \color{brown}\boxed{84}\)

 Jun 17, 2022

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