1. Using the definitions of the position vector r in the rectangular and spherical coordinate systems, show that ∇r = a r .
2. Find the maximum rate of change of a function f = 12x 2 + yz2 with respect to distance at point P(-1, 0, 1). Determine the rate of change
of f in the x, y, and z directions. What is the rate of change of f in the direction of point Q(1, 1, 1) from P?