Consider the biochemical reactor X2 = |B+; B+yx + (1 -B- y)x X2 x = -( - 1)x 1)x + + ( - x)u [B+yx + (1 - By)x Let a = 23, p = 0.39, and y = 0.57. Construct and discuss the phase portrait in the x > 0} when region [X0, u = 0.5 (b) u = 1 (c) u = 1.5 X = x1 U