I was trying to visualize how systems of linear equations in three unknowns work but failed miserably and I started to look for an online tool which would allow me to plot all three equations but surprisingly I could not find one.
Does anyone know of such precious tool?
Have you tried Geogebra 3D. It is not an online tool but it might be just what you need.geogebra
I know they also have an online version of the 2D version but I do not know if they have one of the 3D version yet. Please check the site.