Answer:
-90cm
Explanation:
u=−30cm and magnification m=(−v/u)=−3  so  v=(3u)image is real so m should be negative  v should be negative so v=−90cm
putting the above values of v and u in the Mirror equation,Â
f1=u1+v1
 we get focal length f=−22.5cm and image position v=−90cm
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