1. If $4 x-3 y-6 z=0, x+2 y-7 z=0(x y z \neq 0)$, then the value of the algebraic expression $\frac{5 x^{2}+2 y^{2}-z^{2}}{2 x^{2}-3 y^{2}-10 z^{2}}$ is ( ).
(A) $-\frac{1}{2}$
(B) $-\frac{19}{2}$
(C) -15
(D) -13
-.1.D.
From $\left\{\begin{array}{l}4 x-3 y-6 z=0, \\ x+2 y-7 z=0\end{array}\right.$
we solve to get $x=3 z, y=2 z$. Substituting, we get
$$
\text { original expression }=\frac{5 \times 9 z^{2}+2 \times 4 z^{2}-z^{2}}{2 \times 9 z^{2}-3 \times 4 z^{2}-10 z^{2}}=-13 \text {. }
$$