Is E a Conservative Field? Analyzing Two Fields for Conservation

[kidia]

Can anybody help me on this question,Show whether or not the following fields are conservative:
E=yz^2i+(Xz^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 yz^2=-(x^2-y^2)

 

[Stephan Hoyer]

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