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If π‘₯ + 𝑦 = 5 and π‘₯𝑦 = βˆ’3, then π‘₯2 + 𝑦2 is equal to

 Jun 10, 2017
 #1
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We have  \((x+y)^2=x^2+y^2+2xy\)

 

So  \(x^2+y^2=(x+y)^2-2xy\)

 

Here:  \(x^2+y^2=5^2-2(-3)\text{ ... or ... }x^2+y^2=25+6\rightarrow31\)

 

 

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 Jun 10, 2017

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