Find an equation for the plane tangent to the graph ofz= 6 cos(xy) at the point (2,π/6, 3).

i went on to find

partial derivative x = -6 y sin(xy)

partial derivative y = -6 x sin(xy)

then i used the equation for tangent plane

The thing is, i have no idea if i did this problem correctly or not. I haven't been taught how to deal with problems like this and trying to learn on my own. Can anyone help? Thanks!