The LP relationships that follow were formulated by Richard Martin at the Long Beach Chemical Company. Which ones are invalid for use in a linear programming problem, and why?
Maximize = 6X1 + 12 X1X2 + 5X3
Subject to: 4X1X2 + 2X3 ≤ 70
7.9X1 - 4X2 ≥ 15.6
3X1 + 3X2 + 3X3 ≥ 21
19X2 - 13 X3 = 17
-X1-X2 + 4X3 = 5
4X1 + 2X2 + 3 √X3 ≤ 80