Linear magnification and absolute value?

Question

Linear Magnification value is written "|m| ".My question is why absolute value sign is used?

Answer 1

Magnification per se can be written as a negative value if the image is upside down (when compared to the object).

When going for linear magnification, all we need to know is the relative size, which is always a poitive number. Hence th absolute value bars.

Answer 2

Because the image can be formed right side up (+) or upside-down (-). If all you care about is the size, then you use ||.