SAT Mathematics : Describing Exponential vs. Linear Change

研究概念,例子问题&解释for SAT Mathematics

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Example Questions

Example Question #1 :Describing Exponential Vs. Linear Change

The following equation represents the change of a company’s market value since 1993:. Which of the following statements best describes this function?

Possible Answers:

This company is exponentially growing by

This company is linearly growing by

This company is linearly shrinking by

This company is exponentially shrinking by

Correct answer:

This company is exponentially shrinking by

Explanation:

的correct answer is “This company is exponentially shrinking by.” The above function is an exponential function of t becauseis an exponent of a base in the function. A linear equation would utilizeas a coefficient, not an exponent. The best way to differentiate between growth and shrinkage in an exponential function is to see if the exponent’s base is greater or less than. If the base is, there would be no change inregardless of the value of, but if the base is less than, the company’s value is decreasing.so a loss ofof market value annually.

Example Question #1 :Describing Exponential Vs. Linear Change

Screen shot 2020 09 25 at 11.39.00 am

The above table shows the growth of two plants in cm. Which of the following statements best describes the growth of these two plants?

Possible Answers:

Plant A shows linear growth while Plant B is exponential.

Both Plant A and B show linear growth

Plant A shows exponential growth while Plant B is linear.

Both Plant A and B show exponential growth

Correct answer:

Plant A shows exponential growth while Plant B is linear.

Explanation:

的correct answer is “Plant A shows exponential growth while Plant B is linear.” Each hour doubles the height of Plant A. Doubling is a characteristic of exponential growth. Each hour addscm to the height of Plant B. Additive and subtractive trends are characteristic of linear growth.

Example Question #3 :Describing Exponential Vs. Linear Change

Screen shot 2020 09 25 at 11.41.23 am

Which of the following equations most closely describes the above graph?

Possible Answers:

Correct answer:

Explanation:

的correct answer is. The graph is curved and does not have a defined slope, so it cannot be a linear function. Now, between our exponential functions, we can see that at,, so this must be a coefficient outside of the exponential base. This only leaves. It might be one’s first thought to see that at,, pointing to thechoice, but this equation does not work at any other value of.

Example Question #1 :Describing Exponential Vs. Linear Change

Screen shot 2020 09 25 at 11.44.56 am

Which of the following sets of equations accurately describes the above graph?

Screen shot 2020 09 25 at 11.45.01 am

Possible Answers:

Option 2

Option 4

Option 1

Option 3

Correct answer:

Option 4

Explanation:

Both exponential equations should represent curved lines while the linear equations should be straight lines.shows exponential growth, so asincreases,should increase.shows exponential decay, so asincreases,should decrease. This narrows us down to Option 2 and 4. Within the linear equations,should be a steeper line thansince the slope is greater, thus leaving us with Option 4 as the correct answer.

Example Question #5 :Describing Exponential Vs. Linear Change

The population of moths in a given forest has been decreasing byeveryyears since 2004. The population at the beginning of 2004 was. Ifrepresents the total moth population at timeyears after 2004, which following equations most closely describes the total moth population at any given time?

Possible Answers:

Correct answer:

Explanation:

因为蛾总人口是percentage of the previous period’s population, we know this is an exponential function and not a linear one. We also know that the population has been decreasing. An exponent base ofwould represent no change in the population, while a base of less than one would represent a decrease, so this rules out the option withas the exponent base. The population has been decreasing byso we can say the originalof the population loses, leaving us withof the original population for everyyears that pass. Also, we usebecause the population only decreases byeveryyears. This leaves us with.

Example Question #1 :Describing Exponential Vs. Linear Change

The following equation represents the growth of bacteria in a petri dish:. Which of the following statements best describes this function?

Possible Answers:

This relationship is exponential and doubles every hour.

This relationship is linear and the population of bacteria grows bybacteria every hour.

This relationship is exponential and growstimes larger every hour.

This relationship is linear and the population of bacteria grows bybacteria every hour.

Correct answer:

This relationship is exponential and doubles every hour.

Explanation:

的correct answer is “This relationship is exponential and doubles every hour.” Since the time variableis an exponent, we can narrow down our options and definitively state the function is exponential. Theis an exponent with a base of, so asgrows, the number of timesis multiplied by itself also grows. Each multiplication of two is a doubling of the previous hour’s population (when,vs. when,).

Example Question #1 :Describing Exponential Vs. Linear Change

Which of the following is true about the following function in regards to timein hours:?

我) This is a linear function

2)当,.

我我我) Afterhours,.

Possible Answers:

我and II

我我

我我and III

Correct answer:

我我

Explanation:

的correct answer is II. This is an exponential function, not a linear function. When we plug infor,. When we plug infor,, not.

Example Question #8 :Describing Exponential Vs. Linear Change

米aria has a fruit farm and wants to measure her apple and peach harvest from 2000 to 2020. Her apple harvest grew by approximatelybushels per year while her peach harvest grew bybushels everyyears. In 2003, her apple yield wasbushels while her peach harvest wasbushels. What is the best estimate for the difference between apple and peach harvests in 2018?

Possible Answers:

Correct answer:

Explanation:

的correct answer is. Maria’s apple harvest follows an exponential pattern while her peach harvest is linear. Since time is relative to any given start point, we can call 2003 the year where. Her apple harvest *grows* byso when we convert our percent back to a decimal, we get an exponent base of. Recall, that if her harvest was *losing*of produce yearly, we would use. Since her starting harvest in 2003 wasbushels, we can model her total bushel count as a function of time through the following equation:.

Her peach harvest is a linear function that grows bybushels everyyears. Since time is measured in single years and our growth is given in periods ofyears, be sure to take this into account in your linear equation. Since her starting harvest in 2003 wasbushels, we can model her total bushel count as a function of time through the following equation:.

When we pluginto our equation from subtracting 2003 from 2018, we getbushels of apples andbushels of peaches..

Example Question #1 :Describing Exponential Vs. Linear Change

Which of the following statements are true about an exponential function?

我) It takes the form

我我) It changes at a constant rate per unit interval

我我我) It changes by a common ratio over equal intervals

Possible Answers:

我我

我and III

我and II

Correct answer:

我and III

Explanation:

Exponential functions are in the formwhile linear are. Linear functions change at a constant rate per unit interval while exponential functions change by a common ratio over equal intervals.

Example Question #1 :Describing Exponential Vs. Linear Change

Which of the following statements are true about the exponential function:?

我) The y-intercept of this graph is
我我) The base in this equation is
我我我) The x-intercept of this equation is

Possible Answers:

我and II

我and III

我我

Correct answer:

Explanation:

When(the y-intercept),. The base of this equation is. Exponential functions never have x-intercepts unless they are in the form.

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