Q. The equation $-\frac{x^{2}}{2-\lambda}-\frac{y^{2}}{\lambda-5}-1=0$ represents an ellipse if

Solution:

$-\frac{x^{2}}{2-\lambda}-\frac{y^{2}}{\lambda-5}-1=0$
$\frac{-x^{2}}{(2-\gamma)}-\frac{y^{2}}{(\lambda-5)}=1$
$\frac{x^{2}}{\lambda-2}+\frac{y^{2}}{5-\lambda}=1$
if represents an ellipse if $\lambda-2 > 0\, \&\, 5-\lambda > 0$
$\lambda > 2\, \&\, 5 > \lambda$
$\lambda < 2\, \&\, \lambda < 5$
$\therefore 2 < \lambda < 5$