1
algebra

Maximize P=4x+3yP = 4x + 3y subject to 2x+y102x + y \leq 10, x+2y8x + 2y \leq 8, x,y0x, y \geq 0.

A

2222

B

2020

C

1818

D

2424

Correct Answer: A

Choice A is the correct answer. Find vertices of the feasible region.

  1. Intersection of lines: 2x+y=102x + y = 10 and x+2y=8x + 2y = 8.
    • Multiply second by -2: 2x4y=16-2x - 4y = -16
    • Add to first: 3y=6y=2-3y = -6 \rightarrow y = 2
    • Find x: x+2(2)=8x=4x + 2(2) = 8 \rightarrow x = 4. Vertex (4, 2).
  2. Intercepts:
    • 2x+y=10(5,0)2x + y = 10 \rightarrow (5, 0) and (0,10)(0, 10).
    • x+2y=8(8,0)x + 2y = 8 \rightarrow (8, 0) and (0,4)(0, 4).
    • Feasible region vertices: (0,0),(5,0)(0,0), (5,0) is OUT (fails x+2y8x+2y \leq 8), (4,0)(4,0) is IN? No, wait.
    • Check intercepts against other inequalities:
      • (5,0)(5,0): 5+2(0)=585 + 2(0) = 5 \leq 8 (Valid). So (5,0)(5,0) is a vertex? Wait. 2(5)+0=102(5)+0=10. Yes.
      • (0,4)(0,4): 2(0)+4=4102(0) + 4 = 4 \leq 10 (Valid). So (0,4)(0,4) is a vertex.
  3. Vertices: (0,0),(5,0),(4,2),(0,4)(0,0), (5,0), (4,2), (0,4).
  4. Evaluate P:
    • (0,0):0(0,0): 0
    • (5,0):4(5)+3(0)=20(5,0): 4(5) + 3(0) = 20
    • (4,2):4(4)+3(2)=16+6=22(4,2): 4(4) + 3(2) = 16 + 6 = 22
    • (0,4):4(0)+3(4)=12(0,4): 4(0) + 3(4) = 12
  5. Maximum: 22.

?�� Strategic Tip: The intersection of the boundary lines is often the optimal point.

Choice B is incorrect.Choice C is incorrect.Choice D is incorrect.