Question

ematics 1
The object distance , x cm and the image distance, y cm of a lens are connected by equation 1 /x+ 1 /y= 1/10 . If an object is
moving away from the lens at a rate of 12 cm per minute, find the rate at which the image distance is changing at the instant
when the object distance is 25 cm.
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Answer 1

Answer:

Step-by-step explanation:

2(l+b)=40

l-2b=2

So l=2b +2 ..........(1)

So 2(2b+2+b)=40

2(3b+2)=40

3b+2=20

So b=6cm

And length l =14cm (from (1))