> Convert the following Cartesian equation into cylindrical.?

Convert the following Cartesian equation into cylindrical.?

Posted at: 2014-06-09 
I am having trouble with an assignment stemming from the fact that I'm not sure if my conversion into cylindrical is correct. z = 2*(x^2) + 5*(y^2) My guess is z = 2*(r^2)*cos^2(theta) + 5*(r^2)*sin^2(theta) Conversions are x = r*cos(theta) y = r*sin(theta) r^2 = x^2 + y^2 Can somebody please confirm if this is correct?
That is correct