3. The one-group transport equation in one-dimensional problem is given by -+ (x, ) = (x) + S(x), dy(x, ) dx p(x) = -d y (x,). -1 The P, approximation expands the angular flux with two terms as follows: y (x, ) = $(x) + 36 (x) Q (x) = Ja = (x, ). Please the answer the following questions: (a) Derive the zero'th moment equation by integrating the transport equation after substituting the expansion given above into the transport equation and multiplying 1. (b) Derive the first moment equation by integrating the transport equation after substituting the expansion given above into the transport equation and multiplying (c) Manipulate these two equations to get the diffusion equation and discuss it.