6. Analyzing Functions with Successive Differences
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Type of Function: Linear
| Length of call (min) | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|
| Cost ($) | 0.12 | 0.24 | 0.36 | 0.48 | 0.60 | 0.72 |
Let's plot these data points as ordered pairs on the coordinate plane.
The graph of the ordered pairs seem to be linear.
y=mx+b
Here, m is the slope and b is the y-intercept of the line. From the graph in Part A, we see that the y-intercept is 0. Let's substitute it into the function.
x= 1, y= 0.12
Identity Property of Multiplication
Rearrange equation
The slope of the linear function is 0.12. Then, the function below models the data. y= mx ⇓ y= 0.12x
We found that a 10-minute international call would cost $1.20.