Question 1207031
xy=-7,x+y=10


y=10-x

x(10-x)=-7
10x-x^2=-7
-10x+x^2=7
x^2-10x=-7
x^2-10x+7=0

x=(10+- sqrt(100-4*7))/2

x=(10+- sqrt(72))/2
x=(10+- 6*sqrt(2))/2

x=5+- 3sqrt(2)

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for x=5+3sqrt(2), y=5-3sqrt(2)
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for x=5-3sqrt(2), y=5+3sqrt(2)