Question 23·Medium·Linear Inequalities in One or Two Variables
At a candle-making workshop, is the amount of fragrance oil (in milliliters) and is the amount of dye (in milliliters) used in a test batch. The shaded region on the coordinate plane shows all combinations that meet a quality standard.
Which choice gives an ordered pair that meets the standard?
When the choices are points, first determine the boundary line from two points on the graph, then use the shading and whether the boundary is dashed/solid to decide the inequality. Finally, substitute each answer choice into the inequality (or check each point’s location relative to the boundary) to find the one that satisfies it.
Hints
Read the two labeled points on the boundary
Use the two marked points on the dashed line to compute the slope.
Write the boundary line in slope-intercept form
Find and then write the line as using one of the points.
Remember what dashed shading means
A dashed boundary means points on the line are not included, and shading above the line corresponds to being greater than the boundary’s -value.
Desmos Guide
Graph the boundary line
In Desmos, enter .
Graph the shaded inequality
Enter and note that Desmos shades the solution region above the dashed line.
Test the choices as points
Type each choice as a point, such as . The point that lands in the shaded region is .
Step-by-step Explanation
Find the boundary line equation
From the graph, the dashed boundary line passes through and .
Slope:
Using the point (the -intercept), the line is
Use shading and the dashed boundary
The region is shaded above the boundary line, so is greater than the line’s value.
Because the boundary is dashed, points on the line are not included. Therefore the shaded region satisfies
Test the answer choices
Substitute each ordered pair into .
- For : , so the inequality would be , which is false (it lies on the dashed boundary).
- For : , and is false.
- For : , and is false.
Choose the remaining point
The only choice that satisfies is .