Posted by **SYAZ** on Sunday, May 5, 2013 at 8:42am.

IN A PHYSICS EXPERIMENT,THE DISTANCE OF X AND Y CM HAS A CONNECTION TO EACH OTHER BY 1/X + 1/Y = 1/5.IF THE DISTANCE OF Y IS INCREASING AT THE RATE 16 CMS^(-1),FIND THE RATE OF CHANGE OF THE DISTANCE OF X WHEN Y=9 CM.

- MATH -
**Reiny**, Sunday, May 5, 2013 at 10:09am
So we have

1/x + 1/y = 1/5

differentiate with respect to t

(-1/x^2)dx/dt + (-1/y^2)dy/dt = 0

(-1/x2)dx/dt = (1/y^2)dy/dt

dx/dt = (-x^2/y^2)(dy/dt)

given:

when y = 9

1/x + 1/9 = 1/5

1/x = 4/45

x = 45/4

and dy/dt = ???? , not clear what you mean by

16 CM^(-1)

what ever it is, sub into

dx/dt = (-(45/4)^2 /81) (????)

= (-25/16)(????)

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