susumetomorrow

6/$\sqrt[3]{\frac{x^{9}-9x^{2}+1}{3}}=2x+1$

7/$\left\{\begin{matrix} x^{4}-2x=y^{4}-y & \\ (x^{2}-y^{2})^{3}=3 & \end{matrix}\right.$

8/$\frac{\sqrt{x^{2}-x+2}}{1+\sqrt{-x^{2}+x+2}}-\frac{\sqrt{x^{2}+x}}{1+\sqrt{-x^{2}-x+4}}=x^{2}-1$

3/$x^{4}+2x^{3}+2x^{2}-2x+1=(x^{3}+x)\times \sqrt{\frac{1-x^{2}}{x}}$

4/$\left\{\begin{matrix} 2x^{2}y+3xy=4x^{2}+9y& \\ 7y+6=2x^{2}+9x & \end{matrix}\right.$

5/$\sqrt[3]{\frac{x^{9}-9x^{2}+1}{3}}=2x+1$

1/$-2x^{3}+10x^{2}-17x+8=2x^{2}\times \sqrt[3]{5x-x^{3}}$

2/$3x^{2}+11x-1=13\times \sqrt{2x^{3}+2x^{2}+x-1}$