find the value of x

Answer: [tex]x=5\sqrt{\frac{22}{7\pi}}[/tex]
Step-by-step explanation:
[tex]2\pi (x^2 +2x^2)=471 \frac{3}{7}\\\\3x^2 =\frac{1650}{7\pi}\\\\x^2 =\frac{1650}{21\pi}\\\\x=\sqrt{\frac{1650}{21\pi}}\\\\x=5\sqrt{\frac{22}{7\pi}}[/tex]