Giải các phương trình sau:
1) $x+\sqrt{4-x^2}=2+3x\sqrt{4-x^2}$
2) $\sqrt[3]{81x-8}=x^3-2x^2+\frac{4}{3}x-2$
3) $7x^2+7x=\sqrt{\frac{4x+9}{28}}$, với $x> 0$
4) $x^2+\sqrt{2-x}=2x^2\sqrt{2-x}$
5) $\frac{\sqrt{x^3+1}}{x^2+2}=\frac{2}{5}$
6) $\sqrt{3x^2+6x+7}+\sqrt{5x^2+10x+14}=4-2x-x^2$
7) $\sqrt{x^2-x+19}+\sqrt{7x^2+8x+13}+\sqrt{13x^2+17x+7}=3\sqrt{3}(x+2)$
8) $2\sqrt[4]{27x^2+24x+\frac{28}{3}}=1+\sqrt{\frac{27}{2}x+6}$
9) $\frac{x-3x^2}{2}+\sqrt{2x^4-x^3+7x^2-3x+3}=2$
10) $\sqrt{2-x^2}+\sqrt{2-\frac{1}{x^2}}=4-(x+\frac{1}{x})$
