Answer
See explanation.
Work Step by Step
The mirror equation is $\frac{1}{s}+\frac{1}{s’}=\frac{1}{f}$.
If f is positive (concave spherical mirror), and s is positive, then s’ is positive (real image) as long as the object distance s is greater than f.
For a convex spherical mirror, where f is negative, and s is positive, the image distance s’ is always negative (virtual image) for any value of s. A single convex spherical mirror always produces virtual images.
