Question

verify that (x×y)-1=x-1×y-1 ,where x=2/5,y=-3/8​

Answer 1

Answer:

19. Three lenses in contact have a combined focal length of 12 cm. When the third lens is removed, the combined focal length is 60/7 cm. The third lens is

(1) A converging lens of focal length 30 cm

(2) A converging lens of focal length 60 cm

(3) A diverging lens of focal length 30 cm

(4) A diverging lens of focal length 60 cm

Answer 2

Step-by-step explanation:

LHS=(x×y)-1=(2/5 × -3/8)^-1 = (-3/20)^-1= -20/3

RHS=x-1×y-1 =(2/5)^-1 × (-3/8)^-1 =5/2 × -8/3 = -20/3

therfore, LHS=RHS