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The corner points of the bounded feasible region determined by the system of linear inequalities are (0,0)(0, 0), (2,4)(2, 4), (0,5)(0, 5) and (4,0)(4, 0). If the maximum value of z=ax+byz = ax + by, where a,b>0a, b > 0 occurs at both (2,4)(2, 4) and (4,0)(4, 0), then

Solution

Correct Option: 3

The corner points of the feasible region are (0,0)(0, 0), (2,4)(2, 4), (0,5)(0, 5), and (4,0)(4, 0).

The objective function is z=ax+byz = ax + by where a,b>0a, b > 0.

The maximum value occurs at both (2,4)(2, 4) and (4,0)(4, 0).


In Linear Programming, the maximum value of z=ax+byz = ax + by always occurs at a corner point of the feasible region.

When the maximum occurs at two corner points simultaneously, both points give the same maximum value of zz, and the line z=ax+byz = ax + by is parallel to the edge connecting these two points.


Since the maximum occurs at both (2,4)(2, 4) and (4,0)(4, 0), the value of zz at these points must be equal.

At point (2,4)(2, 4):

z=a(2)+b(4)z = a(2) + b(4)

z=2a+4bz = 2a + 4b

At point (4,0)(4, 0):

z=a(4)+b(0)z = a(4) + b(0)

z=4az = 4a


Setting the values equal:

2a+4b=4a2a + 4b = 4a

4b=4a2a4b = 4a - 2a

4b=2a4b = 2a

2b=a2b = a

Therefore a=2ba = 2b.

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