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Zorluk: OrtaSystems of Linear Inequalities in Two Variables

A landscaping company is planting xx maple trees and yy pine trees in a park. The number of trees of each type must satisfy the system of inequalities below:

30x+40y360x+y10x4\begin{aligned} 30x + 40y &\le 360 \\ x + y &\ge 10 \\ x &\ge 4 \end{aligned}

What is the maximum number of pine trees the company can plant?

Cevap: 6

Cevap

The maximum number of pine trees the company can plant is 6.
To find the maximum number of pine trees, yy, we look at the boundary constraints. The constraint x4x \ge 4 states that at least 44 maple trees must be planted. Since planting fewer maple trees leaves more of the budget for pine trees, we minimize xx by setting x=4x = 4. Substituting this value into the budget inequality 30x+40y36030x + 40y \le 360 gives 120+40y360120 + 40y \le 360. Solving for yy yields 40y24040y \le 240, which simplifies to y6y \le 6. We then verify that the solution (4,6)(4, 6) satisfies the total tree constraint x+y10x + y \ge 10, which it does since 4+6=104 + 6 = 10. Thus, the maximum number of pine trees is 6.

Adım Adım Çözüm

1
Substitute the minimum possible value of xx into the first inequality.
Since x4x \ge 4, the smallest possible value for xx is 44. Substituting x=4x = 4 into 30x+40y36030x + 40y \le 360 yields:
30(4)+40y36030(4) + 40y \le 360
120+40y360120 + 40y \le 360
To maximize the value of yy under the resource constraint, we must minimize the value of xx.
2
Solve the inequality for yy.
40y24040y \le 240
y6y \le 6
This establishes that the maximum possible value for yy based on the budget constraint is 66.
3
Verify that (4,6)(4, 6) satisfies all inequalities in the system.
Checking the second inequality: x+y10    4+6=1010x + y \ge 10 \implies 4 + 6 = 10 \ge 10, which is true. The third inequality x4    44x \ge 4 \implies 4 \ge 4 is also true.
A coordinate pair must satisfy all inequalities in the system to be a valid solution.

Anahtar Kavram

To find the maximum value of a variable in a system of inequalities with constraints, analyze the boundary lines and the intersection points of the feasible region.
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