Pauley graphs the change in temperature of a glass of hot tea over time. He sees that the function appears to decrease quickly at first, then decrease more slowly as time passes. Which best describes this function?
Answer
A
It is linear because the graph decreases over time.
B
It is linear because there is both an independent and a dependent variable.
C
It is nonlinear because linear functions are increasing functions.
D
It is nonlinear because linear functions increase or decrease at the same rate.
Explanation
A linear function changes at a constant rate, so its graph has a constant slope. The tea’s temperature decreases quickly at first and then more slowly, meaning its rate of change is not constant. Therefore, the function is nonlinear; choice D correctly describes why.
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