Soru

Zorluk: Çok zorSystems of Linear Inequalities in Two Variables

In the xyxy-plane, a point (x,y)(x, y) is in the solution set of the system of inequalities below:

x2y6x - 2y \leq -6
x+y11x + y \leq 11
y5y \leq 5

What is the maximum possible value of xx?

Cevap: 4

Cevap

The maximum possible value of xx is 44.
The maximum possible value of xx is 44. For all points in the solution set where y5y \leq 5, the active upper bound is x2y6x \leq 2y - 6. Since 2y62y - 6 increases as yy increases, the maximum value of xx occurs at the maximum boundary y=5y = 5, giving x=2(5)6=4x = 2(5) - 6 = 4.

Adım Adım Çözüm

1
Express xx in terms of yy using the first two inequalities.
x2y6x \leq 2y - 6 and x11yx \leq 11 - y
To isolate the variable xx and analyze how its upper bound is constrained by yy.
2
Apply the third inequality constraint, y5y \leq 5, to find the limits on these upper bounds.
2y642y - 6 \leq 4 and 11y611 - y \geq 6
Since yy cannot exceed 55, the value of 2y62y - 6 is maximized when y=5y = 5, and 11y11 - y is minimized when y=5y = 5.
3
Compare the two upper bounds to determine the active constraint for the domain y5y \leq 5.
Since 2y642y - 6 \leq 4 and 11y611 - y \geq 6, the active bound is x2y6x \leq 2y - 6.
For any point to satisfy the system, xx must be less than or equal to both bounds, meaning it is restricted by the smaller of the two bounds.
4
Calculate the maximum value of xx at the boundary point.
x=4x = 4 at the point (4,5)(4, 5)
The function 2y62y - 6 is increasing with respect to yy, so its maximum value occurs at the largest possible value of yy, which is 55.

Anahtar Kavram

Finding the maximum value of a coordinate within a system of linear inequalities.
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