The pressure distribution in a deep sea changes with water streams, depth and temperature distribution. The pressure distribution is a scalar function p(x, y, z), and is given as 4 p(x, y, z)=P-pgz + xyd In this equation Po, p, g and d are constants. Accordingly, evaluate a) The maximum rate of increase of pressure at a depth of A(1, 1, -1) in terms of Po, p, g and d. b) The derivative of pressure at a depth of A(1, 1, -1) in the direction of u=i+j+k. c) div(grad P)=? d) curl(grad P)=?