10. Two different parabolas $y=x^{2}+k x+1$ and $y=x^{2}-x-k$ pass through the same point on the $x$-axis when the value of the real number $k$ is $\qquad$.
10. $k=2$.
$x^{2}+k x+1=x^{2}-x-k$, that is, $(k+1) x=-(k+1)$. If $k=-1$, then the two parabolas are the same, so $k \neq$ $-1, x=-1$. Thus $y=2-k$, let $y=0$, we get $k=2$.