I need help with part (e.), particularly why F is one to one on the interior

3. Let f(x, y, z) = x(1 -x - y - z)s, where s 2 0 is a parameter. a) [3 marks] Sketch the region of integration ? for the following triple integral, -x-y f(x, y, z) dV = f(x, y, z) dz dy dx. b) [3 marks] Evaluate the repeated integral from a) for the special case when S = 0. c) [3 marks] Evaluate the repeated integral from a) for the special case when S =1. d) [2 marks] The change of variables defined by the relations cty tz = u, y tz= uv, z = uvw. maps the region I defined by 0