Hi there I need help with one of the problem from my homework package. This week for my calculus class, we were learning how to do partial derivative and finding the tangent of the plane. So I do not know how to approach this problem. Please help me by how to derive this problem:

Question

Let z=xsin(x/y), Which y cannot equal to zero. Show that the tangent plane at any point of the surface passes through the origin of (0,0,0).