1.
Choice A is not exponential growth or decay because the cost will go up by the same amount ($2) each time. Choices B and C are exponential, but they aren't growth functions. Rather, they are decay functions. A disease spreads exponentially because one person infects two, and then each of those two people infect two others (making 4 additional people infected), and so on.
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2.
Assuming the treatment works and it is effective, then the cancer cells will go away over time. One example would be that the population is cut in half each time. Choice A is not an answer because the balance will go down the same amount each time. This is assuming the bus company does not change its prices. Choices B and D are eliminated because they represent growth.
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3.
I'm unable to answer this because the table is missing.
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4.
If the y values increase or decrease by the same amount, as x increases by some set amount, then you have a linear function. For example, if x increases by 1 pairs up with y increasing by 4, then the slope is 4/1 = 4 and we have a linear function.
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On the other hand, if x increases by 1 couples with the y values multiplying by some set amount, then you have an exponential function.
Example:
Each time x increases by 1, y is multiplied by 5.
