Assume a flux of a quantity given by the density u(x, t) on the real line is given by ф(x) = sin(2πx). determine the following 1. assume r(x) = 0. specify all regions on the real line where the density u is growing, shrinking, or staying the same. 2. assume the system is in equilibrium at every point on the real line. determine r(x). specify on what regions of the line is there a source and sink.