Skip to main contentSkip to solution

Consider the LPP: Maximize z=5x+3yz = 5x + 3y subject to 3x+5y≤153x + 5y \leq 15, 5x+2y≤105x + 2y \leq 10, x,y≥0x,y \geq 0. The optimal feasible solution occurs at

Solution

✅ Correct Option: 4

The maximum value of z=5x+3yz = 5x + 3y occurs at a corner point of the feasible region formed by the constraints.


The corner points are found by checking the origin, axis intersections, and constraint line intersections.

At the origin: (0,0)(0, 0)


For the intersection with the x-axis, set y=0y = 0:

From 3x+5y≤153x + 5y \leq 15: x≤5x \leq 5

From 5x+2y≤105x + 2y \leq 10: x≤2x \leq 2

The binding constraint gives the corner point: (2,0)(2, 0)


For the intersection with the y-axis, set x=0x = 0:

From 3x+5y≤153x + 5y \leq 15: y≤3y \leq 3

From 5x+2y≤105x + 2y \leq 10: y≤5y \leq 5

The binding constraint gives the corner point: (0,3)(0, 3)


For the intersection of the two constraint lines:

3x+5y=153x + 5y = 15 ... (1)

5x+2y=105x + 2y = 10 ... (2)

Multiply equation (1) by 2: 6x+10y=306x + 10y = 30

Multiply equation (2) by 5: 25x+10y=5025x + 10y = 50

Subtracting: 19x=2019x = 20

x=2019x = \dfrac{20}{19}

Substituting into equation (2):

5⋅2019+2y=105 \cdot \dfrac{20}{19} + 2y = 10

10019+2y=10\dfrac{100}{19} + 2y = 10

2y=90192y = \dfrac{90}{19}

y=4519y = \dfrac{45}{19}

The corner point is: (2019,4519)\left(\dfrac{20}{19}, \dfrac{45}{19}\right)


Evaluating z=5x+3yz = 5x + 3y at each corner point:

At (0,0)(0, 0): z=0z = 0

At (2,0)(2, 0): z=10z = 10

At (0,3)(0, 3): z=9z = 9

At (2019,4519)\left(\dfrac{20}{19}, \dfrac{45}{19}\right):

z=5⋅2019+3⋅4519z = 5 \cdot \dfrac{20}{19} + 3 \cdot \dfrac{45}{19}

z=100+13519z = \dfrac{100 + 135}{19}

z=23519≈12.37z = \dfrac{235}{19} \approx 12.37


The maximum value is 23519\dfrac{235}{19}, occurring at the point (2019,4519)\left(\dfrac{20}{19}, \dfrac{45}{19}\right).

Keyboard Shortcuts

  • Left arrow: Previous question
  • Right arrow: Next question
  • S key: Jump to solution
  • Q key: Jump to question