Question 855315
First one:  z varies jointly as x to the half power and inversely as y squared.

Second one:  I will not do this one for you, but it is too a variation  of how z varies with x and y and shows the same proportionality constant, k.  If an "independent" variable is in a numerator position, it is "jointly"; and if an independent variable is in  a denominator position, it is "inversely".