IE121 Exercise 2.1 Duality in LP Answer the following problems on the space provided and save it as pdf. 1. (4 points) Write the dual to the following problem. Maximize z = 2x1 + x2 + 3x3 + x4 subject to x1 + x2 + X3+X4 5 2x1 x2+3x3 = -4 xX1-X3+ X4 1 X1, X3 0 X2, X4 unrestricted