\(x+\left(\frac{-31}{12}\right)^2=\left(\frac{49}{12}\right)^2-x\)

<=>\(x+x=\frac{31^2}{12^2}+\frac{49^2}{12^2}\)

<=>\(2x=\frac{3362}{144}=\frac{1681}{72}\)

<=>\(x=\frac{1681}{144}\)

=>\(y^2=x+\left(-\frac{39}{12}\right)^2=\frac{1681}{144}+\frac{1521}{144}=\frac{1601}{72}\Rightarrow y=^+_-\sqrt{\frac{1601}{72}}\)