Bài 1 : $\sqrt{x+2} - y^{3} = \sqrt{y+2} - x^{3}$
$ \Leftrightarrow (\sqrt{x+2} - \sqrt{y+2} ) + ( x^{3} - y^{3}) = 0$
$ \Leftrightarrow \frac{x+2-y-2}{\sqrt{x+2} + \sqrt{y+2}} + ( x - y ) (x^{2} -xy+y^{2}) = 0$
$ \Leftrightarrow \left ( \frac{1}{\sqrt{x+2} + \sqrt{y+2} }+ x^{2} - xy + y^{2}\right ) ( x - y ) = 0$
$ \Rightarrow x = y$ Thay vào B
$ \Rightarrow B = x^{2} + 2x^{2} - 2x^{2} + 2x + 10$
$ = ( x + 1 )^{2} + 9 \geq 9$
Suy ra Min B = 9 $ \Leftrightarrow $ x = y = -1