an object 5 millimeters high is loacated 15 millimeters in front of a plane mirror. how far from the mirror is the image located?

Answer 1

Can someone check me on this please.

the formula is:

1/d1 = (1/f)-(1/d0)

where
d1 = image distance
f = focal length of the mirror(object height)
d0 = object distance from the mirror

giving you:
1/d1 = (1/15mm) - (1/5mm)
1/d1 = -0.1333333 recurring

take the inverse of this number giving:
d1(image distance) = -0.1333333^-1
d1(image distance) = -7.5mm

Answer 2

If it is a plane mirror the image appears to be as far behind the mirror as the object is in front.