This is 0 which implies, but del u by del x plus del v by del y plus del w by del z is equal to 2 c y minus 2 c y that is 0. So, since this is 0, so we can always say that the velocity
field that represented by u is equal to 2 c x y, v is equal to 2 c into a square plus x square minus y square and w is equal to 0 represents the flow of an incompressible fluid. Now, with this example I will give some of the example for you to work it out at room, in your home that I will just give you a homework.