Question 84
It is known that nonzero real numbers $x$, $y$, $z$ satisfy the condition $xy + yz + zx = 0$. What value can the expression
$$
\frac{1}{x^2+2yz} + \frac{1}{y^2+2zx} + \frac{1}{z^2+2xy}
$$
be equal to?
$$
\frac{1}{x^2+2yz} + \frac{1}{y^2+2zx} + \frac{1}{z^2+2xy}
$$
be equal to?