Now, I will go to another example suppose, I will say suppose u is equal to two c x y and my v is equal to c into a square plus x square minus y square and my w is 0. If this is the case here also u v w are independent this is my example 2. So, in this case also u v w are they are all independent of rho. So, it can be easily seen that d rho by d t is 0, then we have we have del u by del x is equal to 2 c y del u by del y minus 2 c y and you have del w by del z where w is 0.