Ta có:
\(x+\left(-\frac{31}{12}\right)^2=\left(\frac{49}{12}\right)^2-x\)
\(\Rightarrow2x+\frac{961}{144}=\frac{2401}{144}\)
\(\Rightarrow2x=\frac{2401}{144}-\frac{961}{144}\)
\(\Rightarrow2x=\frac{1440}{144}\)
\(\Rightarrow2x=10\)
\(\Rightarrow x=5\)
Vậy \(x=5\)