For each function f(x, y,z), determine whether its gradient points radially outward from the origin, radially inward toward the origin, radially outward from the z-axis, or radially inward toward the z-axis.1. f(x, y,z) = x^2 + y^2(a) Points radially outward from the origin (b) Points radially inward toward the origin (c) Points radially outward from the z-axis