Answer
(a) $2.5cm$
(b) $-5.0cm$
Work Step by Step
(a) We can find the required object distance as
$d_{\circ}=(\frac{m-1}{m})f$
We plug in the known values to obtain:
$d_{\circ}=(\frac{2-1}{2})(5.0cm)$
$d_{\circ}=2.5cm$
(b) We can find the image location as
$d_i=-md_{\circ}$
We plug in the known values to obtain:
$d_i=-2(2.5cm)$
$d_i=-5.0cm$
