Given that the three
variables x,y, and z are related by the rule z= kxy with k>0.
This means that x and y are directly proportional to z.
Given that x > 0 and y > 0
For values that are directly proportional, an increase in the independent variable leads to an increase in the dependent variable and a decrease in the independent variable leads to a decrease in the dependent variable.
Therefore, the value of z will increase if x is
held constant and y increases.
And the value of z will decrease if x is held constant and y decreases.
