when using the lens equation, a negative valu...

# Brief Explanations: In optics, when the image - distance ($d_i$) calculated using the lens equation is negative, it means the image is formed on the same side of the lens as the object. By definition, such an image is virtual. Real images have positive $d_i$ values. The sign of $d_i$ does not directly tell about the orientation (upright or inverted) of the image. Orientation is related to the magnification sign. # Answer: virtual.