Question 41·Medium·Linear Equations in Two Variables
The graph shows a relationship between water temperature, , (in degrees Celsius) and dissolved oxygen, , (in milligrams per liter) in a sample.
Which equation could represent the line shown in the graph?
When a line is shown on a graph, choose two clear points on the line (often labeled) and compute the slope. Then use point-slope form with one of the points to write the equation, and rewrite it into the same form as the answer choices to select the match.
Hints
Pick two clear points
Use the two labeled points on the line to compute the slope.
Use the slope formula
Compute using the two points.
Use point-slope form
Once you have the slope , plug one point into , then rewrite to match an answer choice.
Desmos Guide
Plot the two points
In Desmos, enter the points and and visually confirm the line goes through them.
Graph each answer choice
Enter each equation (for example, ) to see its line.
Check which line matches the graph
The correct equation’s graph must pass through both and and slope downward from left to right.
Step-by-step Explanation
Read two points from the graph
The line passes through the labeled points and .
Find the slope
Compute the slope:
Write an equation and convert to standard form
Use point-slope form with :
Distribute and simplify:
Multiply by and rearrange:
So the equation that could represent the line is .