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If x + y =2 and xy = 23, then what is x^2 + y^2?

Guest Jan 31, 2015

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 #1
avatar+91448 
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x + y =2    and xy = 23, then what is x^2 + y^2?

 

$$\\(x+y)^2=x^2+y^2+2xy\\
so\\
x^2+y^2=(x+y)^2-2xy\\
x^2+y^2=2^2-2*23\\
x^2+y^2=4-46\\
x^2+y^2=-42\\$$

Melody  Jan 31, 2015
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1+0 Answers

 #1
avatar+91448 
+5
Best Answer

x + y =2    and xy = 23, then what is x^2 + y^2?

 

$$\\(x+y)^2=x^2+y^2+2xy\\
so\\
x^2+y^2=(x+y)^2-2xy\\
x^2+y^2=2^2-2*23\\
x^2+y^2=4-46\\
x^2+y^2=-42\\$$

Melody  Jan 31, 2015

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