Question

please answer the a) part

Answer 1

Hey....
Magnification =-v/u
3=-v/u
v=-30
Now, using this formula 1/f=1/u+1/v
1/f=1/-10+1/-30(since u and f of concave mirror is negative)
1/f=1/-10+1/-30
1/f=4/-30
f= -30/4 cm.
Hope this helps you!!!!