Recall the proper formula of mirror formula, f1=v1+u1, given f=−10cm and u=−5cm then the formula of the concave mirror, −101=v1−51⇒v=−10cm. As, image copies the time period of the object (A) is right as well. It will be a periodic motion. For one extreme,
⇒−81+v1=−51⇒v=−340cm, right arrow.
For other extreme,
⇒−121+v1=−51⇒v=−607cm. These points are asymmetrical about x0=10cm. Now amplitude of oscillation of image, ⇒340−760=21100cm.