Question Details

Maximize Z = 6x + 4y, subject to x ≤ 2, x + y ≤ 3, -2x + y ≤ 1, x ≥ 0, y ≥ 0

Options

A

12 at (2, 0)

B

140/3 at (2/3, 1/3)

C

16 at (2, 1)

D

4 at (0, 1)

Correct Answer :

16 at (2, 1)

Solution :

The correct option is 16 at (2, 1).

To find the maximum value of the objective function Z=6x+4y subject to the given constraints, we can use the graphical method of linear programming. First, we identify the feasible region determined by the following inequalities:
1. x2
2. x+y0 (implied by non-negativity) and x+y3
3. -2x+y1
4. x0, y0

Let us find the boundary lines and their intersection points to determine the corner points (vertices) of the feasible region:
- The line x=0 is the y-axis, and y=0 is the x-axis.
- The line x=2 is a vertical line passing through (2,0).
- The line x+y=3 intersects the axes at (3,0) and (0,3).
- The line -2x+y=1 intersects the axes at (-0.5,0) and (0,1).

Next, we solve for the intersection points of these boundary lines that lie in the first quadrant (x0, y0):
- Intersection of x=0 and -2x+y=1 gives the corner point A(0,1).
- Intersection of -2x+y=1 and x+y=3:
Subtracting the first equation from the second equation:
(x+y)-(-2x+y)=3-1
3x=2x=23
Substituting x=23 into x+y=3 gives y=3-23=73. This gives the corner point B(23,73).
- Intersection of x+y=3 and x=2:
Substituting x=2 into the equation gives 2+y=3y=1. This gives the corner point C(2,1).
- Intersection of x=2 and the x-axis (y=0) gives the corner point D(2,0).
- The origin O(0,0) is also a corner point.

The bounded feasible region is defined by the vertices O(0,0), A(0,1), B(23,73), C(2,1), and D(2,0).

Now, we evaluate the objective function Z=6x+4y at each of these corner points:
1. At O(0,0): Z=6(0)+4(0)=0
2. At A(0,1): Z=6(0)+4(1)=4
3. At B(23,73): Z=6(23)+4(73)=4+283=40313.33
4. At C(2,1): Z=6(2)+4(1)=12+4=16
5. At D(2,0): Z=6(2)+4(0)=12

Comparing these values, the maximum value of Z is 16, which occurs at the point (2,1).

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