Question

1/f=1/v-1/u ;v=25 u=-100

Answer 1

Answer:

If 1/f=1/v-1/u. then,

v=25,u=-100

1/f=1/25-1/-100

1/f=1/25+1/100

1/f=1/25*4/4+1/100

1/f=4+1/100

1/f=5/100

1/f=1/20

.•.f=20

Answer 2

Answer:

75

Step-by-step explanation:

1/f=1/v-1/u

1/f=1/25-1/100

100-25

=75