5
algebra

Find the minimum value of C=4x+5yC = 4x + 5y in the region with vertices (0,6)(0, 6), (4,2)(4, 2), and (7,0)(7, 0) bounded by x,y0x, y \geq 0.

A

2626

B

3030

C

2828

D

00

Correct Answer: A

Choice A is the correct answer. Test the vertices.

  1. (0, 6): C=4(0)+5(6)=30C = 4(0) + 5(6) = 30
  2. (4, 2): C=4(4)+5(2)=16+10=26C = 4(4) + 5(2) = 16 + 10 = 26
  3. (7, 0): C=4(7)+5(0)=28C = 4(7) + 5(0) = 28
  4. Minimum: 26 is the lowest value.

?�� Strategic Tip: Don't assume the vertex closest to the origin is the minimum; coefficients matter.

Choice B is incorrect because 30 is the maximum. Choice C is incorrect because 28 is not the minimum. Choice D is incorrect because(0,0)(0,0) is not a vertex of this region.