JEE Main 2021 (Online) 17th March Evening ShiftQuestion 151
Let $P$ be an arbitrary point having sum of the squares of the distances from the planes $x+y+z=0$, $lx-nz=0$ and $x-2y+z=0$, equal to $9$. If the locus of the point $P$ is $x^{2}+y^{2}+z^{2}=9$, then the value of $l-n$ is equal to $\_\_\_\_\_\_$ .
3D Geometry