A table of corresponding - and -values represents a linear relationship when the ratio of the change in to the change in , , is constant; this rate of change is the slope and may be positive, negative, or zero. The slope can be determined from any two ordered pairs in the table, including when -values are not consecutive, while distinguishing it from or from the un-reversed change in ; more advanced treatments of nonlinear data or undefined slope are not included.
Slope tells how much changes for each change in . For a table, use two corresponding ordered pairs and calculate
Always subtract in the same order: if you use the second minus the first , also use the second minus the first .
Suppose the table shows:
Step 1: Choose two points.
Use and . The -values do not need to be next to each other in the table.
Step 2: Find the change in .
Step 3: Find the change in .
Step 4: Divide the change in by the change in .
The slope is . This means that for every increase of in , increases by .
Do not calculate ; slope is the ratio of the changes, . Since the table represents a linear relationship, any two points should give the same slope.
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