Exponential Functions Y-Intercept and Rate of Change

Does the graph represent an exponential growth or an exponential decay function?

• Exponential Growth
• Exponential Decay

What does the y-intercept of the graph represent?

• The amount of grams the material is gaining.
• The amount of grams the material is losing.
• The amount of grams remaining after so many years.
• The initial amount of grams.

Which of the following is an increasing exponential function whose y-intercept is 50?

• y = 50(.05)^x
• y = 50x - 4
• y = (2)^x + 50
• y = 50(1.4)^x

The amount of ants in a colony, f(x), that is decaying can be modeled by f(x) = 800(.87)^x, where x is the number of days since the decay started. Suppose f(20) = 49. Which of the following is true?

• After 20 days, there are 49 ants in the colony.

• After 49 days there are 20 ants in the colony.

• The amount of ants times 20 is 49.

• After 20 days the amount of ants remaining decreases by 49.

The expression 12(1.015)^t models the population of elephants in a wildlife refuge after t years since 1975.
Is the population of elephants increasing or decreasing?

• Increasing
• Decreasing

The expression 12(1.015)^t models the population of elephants in a wildlife refuge after t years since 1975.
What does the value 12 represent?

• The predicted increase in number of elephants in the refuge each year.
• The predicted decrease in number of elephants in the refuge each year.
• The number of years it will take for the elephant population to stop increasing.
• The initial amount of elephants in the park.

The equation f(t) = 12(1.015)^t models the population of elephants in a wildlife refuge after t years since 1975.

What does the value 1.015 represent?

• The number of elephants was 1,015 in 1975.

• The number of elephants increases by 1.5% each year.

• The number of elephants increases by 101.5% each year.

• The number of elephants is multiplied by 1.015 each year.

The amount of ibuprofen (medicine for headaches) breaks down by 30% each hour. Would this real world situation be modeled as exponential growth or decay?

• exponential growth

• exponential decay

Is the graph exponential growth or decay?

• Exponential growth
• Exponential decay

Is the following function exponential growth, exponential decay, linear, or none of the above.

g(x) = 740(.91)^x

• Exponential growth

• Exponential decay

• Linear

• None of the above