Are these two vector fields conservative?

[kidia]

Can anybody help me on this question,Show whether or not the following fields are conservative:
E=y$$z^2$$$$i$$+(X$$z^2$$+2)j+(2xyz-1)k

E=-($$x^2$$-$$y^2$$)i-2xyj+4k

I don't think if am right I want to start by comparing i follow by j and z,example y$$z^2$$=-($$x^2$$-$$y^2$$)

 

[Stephan Hoyer]

To test if a field is conservative, you can take the curl...