Question

find the focal length of
u= -100
v= +25​

Answer 1

Answer:

I think 33.333

Explanation:

1/f=1/u+1/v

=-1/100+1/25

=-1+4/100

=3/100

f=100/3

f=33.333

Answer 2

Answer:

1/f = 1/v +1/u

=1/25 +(1/-100)

=1/25 -1/100

=4-1/100

= 3/100

=0.03