Question

Difficulty: EasySystems of Linear Inequalities in Two Variables

A solution to a system of inequalities in the xyxy-plane is represented by the point (2,y)(2, y). If the system is defined by:

y4x2y \geq 4x - 2
y2x+10y \leq -2x + 10

what is the value of yy?

Answer: 6

Answer

The value of yy must be exactly 6 because it is bounded both below and above by 6.
Substituting x=2x = 2 into the system of inequalities yields two constraints: y4(2)2y \geq 4(2) - 2, which simplifies to y6y \geq 6, and y2(2)+10y \leq -2(2) + 10, which simplifies to y6y \leq 6. The only value of yy that satisfies both statements is 6.

Step-by-Step Solution

1
Substitute x=2x = 2 into the first inequality y4x2y \geq 4x - 2
y6y \geq 6
To determine the constraint on the yy-value from the first inequality at the coordinate x=2x = 2.
2
Substitute x=2x = 2 into the second inequality y2x+10y \leq -2x + 10
y6y \leq 6
To determine the constraint on the yy-value from the second inequality at the coordinate x=2x = 2.
3
Find the value of yy that satisfies both y6y \geq 6 and y6y \leq 6
y=6y = 6
For a value to be simultaneously greater than or equal to 6 and less than or equal to 6, it must be equal to 6.

Key Concept

Evaluating a system of linear inequalities at a specific coordinate to determine a unique boundary value
Estimated Time:45s
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