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📐 Mathematics  ·  Linear Programming  ·  JEE

For the LPP Maximize Z = 5x + 4y subject to 3x + y <= 12 and x + 2y <= 10, x,y >= 0, the corner points include (0,0), (4,0), (0,5), and the intersection of the two boundary lines. Find Z at that intersection point.

Answer: 28.4.

  • A 20
  • B 30
  • C 28.4
  • D 24

Correct answer: C. 28.4

Explanation: Solving 3x+y=12 and x+2y=10 together gives x=2.8, y=3.6. Then Z = 5(2.8)+4(3.6) = 14+14.4 = 28.4, the maximum value of Z over the feasible region.

Feasible Region and Corner PointsxyOABCfeasible regionZ = ax+by is evaluated ONLY at corners O, A, B, C - the optimum is always at one of these

The feasible region (shaded) is bounded by the constraint lines; the fundamental theorem of LPP guarantees the optimal value of the objective function occurs at one of the corner points (O, A, B, C), so only these need to be checked, not the entire region.

Concept context

Optimizing a linear objective function subject to linear constraints using the graphical corner point method.

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