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April 8th, 2014, 05:46 PM   #1
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4(x^2+4)=9+12x

^ is a power sign so x^2 is x squared

4(x^2+4)=9+12x

4x^2+16=9+12x

4x^2-12x+7=0

divide all by 4

x^2-3x+7/4=0 i am stuck here

the answer sheet says this is the answer

3 +or- √2
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April 8th, 2014, 06:16 PM   #2
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Use the quadratic formula.
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April 8th, 2014, 09:32 PM   #3
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So using that formula it eventually gets to
12+or- 4√2
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then if thats correct how do you continue to get?

3+or- √2
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April 8th, 2014, 09:35 PM   #4
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Math Focus: Calculus/ODEs
Factor a 4 from the numerator, and then cancel or divide out common factors:

$\displaystyle \frac{12\pm4\sqrt{2}}{8}= \frac{\cancel{4}\left(3\pm\sqrt{2} \right)}{\cancel{4}\cdot2}= \frac{3\pm\sqrt{2}}{2}$
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