Cho x, y, z $\epsilon \mathbb{R}$ đôi 1$\neq$ nhau tm:
$\left ( y-z \right )\sqrt[3]{1-x^{3}} + \left ( z-x \right )\sqrt[3]{1-y^{3}}+\left ( x-y \right )\sqrt[3]{1-z^{3}}=0$
CMR: $\left ( 1-x^{3} \right )\left ( 1-y^{3} \right )\left ( 1-z^{3} \right )=\left ( 1-xyz \right )^{3}$