\begin{array}{c} {x^{2} \plus{} y^{2} \plus{} z^{2} \equal{} 21} \\
{x \plus{} y \plus{} z \plus{} xyz \equal{} \minus{} 3} \\
{x^{2} yz \plus{} y^{2} xz \plus{} z^{2} xy \equal{} \minus{} 40} \end{array}
The number of real triples (x,y,z) satisfying above system is <spanclass=′latex−bold′>(A)</span> 0<spanclass=′latex−bold′>(B)</span> 3<spanclass=′latex−bold′>(C)</span> 6<spanclass=′latex−bold′>(D)</span> 12<spanclass=′latex−bold′>(E)</span> None algebrapolynomialquadratics