SOLUTION: z varies directly as x^2 and inversely as y^2 . If z�=�165 when x�=�4 and y�=�7 , find z if x�=�9 and y�=�6 . (Round off your answer to the nearest hundredth.)

Question 1059524: z varies directly as x^2 and inversely as y^2 . If z�=�165 when x�=�4 and y�=�7 , find z if x�=�9 and y�=�6 . (Round off your answer to the nearest hundredth.)
Answer by Edwin McCravy(20054) (Show Source): You can put this solution on YOUR website!
z varies directly as x^2 and inversely as y^2 . If z�=�165
when x�=�4 and y�=�7 , find z if x�=�9 and y�=�6 . (Round
off your answer to the nearest hundredth.)


For all proportion problems, start with this:

Varying           "directly" or product of "jointlys" or 1 if none 
quantity  = k � ----------------------------------------------------------
                inversely variable or product of "inverselys" or 1 if none

In this problem the varying quantity is z.
We have one "directly", x�.  We have one inversely, y�.  So we have x� 
on top and y� on the bottom:

z = k�

one set of values is

z�=�165 when x�=�4 and y�=�7
Substitute these values: 165 = k� 165 = k� Multiply both sides by = k Now substitute for k in the first equation: z = k� z = � >>...find z if x�=�9 and y�=�6 ...<< Substitute those values z = � z = � z = 1136.953125 Round to z = 1136.95 Edwin

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