**Y Varies Jointly With X And Z**. Y varies directly as x and. We know that the function has the form z = kxy, so k = z xy.

We know that the function has the form z = kxy, so k = z xy. Jun 29, 2015 the function is z = 2xy. If y = 192 y=192 y = 192 when x = 2 x=2 x = 2 and z = 3 z=3 z = 3, then 192.