
$\begin{aligned}
-\frac{1}{f_{e q}} & =\frac{2}{f_l}-\frac{1}{f_m} \
& =2(\mu-1) \frac{2}{R}+\frac{2}{R} \
-\frac{1}{f_{e q}} & =\frac{2(2 \mu-1)}{R} \
f_{e q} & =-\frac{R}{2(2 \mu-1)}
\end{aligned}Forconcavemirror,objectshouldbeat2 ffortheimagetobeatsamepoint\text { Distance }=\frac{R}{(2 \mu-1)}$