This question just seems somewhat unclear.
Asking for symmetric and parametric equations for the z axis means to have x and y equaling zero?
Okay, so then the equations would be as follows:
(x-0)/0 = (y-0)/0 = (z-0)/1
Although the symmetric equations of x & y are ÷ 0 which is not allowed. So how would do you change it so they are not?
Multiply all by zero to give x=y=0?
Thank you very much for your help!