Consider the following general equilibrium model with two competitive goods markets. In market 1, demand and supply are equal to Q_D1 = a-bP₁ - eP₂ and Q_s1 = -f + gP_1, respectively. In market 2, demand and supply are equal to Q_D2 = -P₁ - P₂ and Q_s = - + yP₂

All parameters are strictly positive. a) Express the equilibrium condition in matrix form. b) Using an echelon matrix, derive the condition under which a unique equilibrium exists. c) Interpret this condition in terms of mathematics. d) Using a graph, illustrate what happens if the condition derived in part b) is violated (there are two cases that you will want to cover).