Å„Å‚
òÅ‚x = x2
1
ółx = -x1
2
Å„Å‚
ôÅ‚x = 1
ôÅ‚
ôÅ‚
òÅ‚
z
ôÅ‚y = (z-y)2
ôÅ‚
ôÅ‚
ółz = y
(z-y)2
(z - y)ux + (x - z)uy + (y - x)uz = 0
xux + 2yuy + 3zuz = 0
ux - (y + 2z)uy + (3y + 4z)uz = 0
ux + uy + uz = u u(x, y, 0) = x2 + y2
“ = {(x, y, 0) : x, y " R}