Exponential Functions and Interest

Which of the following is an exponential function?

• y = x²

• f(x) = 3x³

• y = x³

• f(x) = 3^x

What is the y-intercept in y=4(2)^x

• (4,0)

• (0,2)

• x

• (0,4)

• (4,2)

What is the starting amount in the problem below?

f(t) = 300(1.05)^t

• 300

• 1.05

• t

• y

The y-intercept for any function in the form

y=b^x

• (0,0)

• (0,1)

• (1,0)

What is the range of this function?

• (-∞,0)

• (0,∞)

• (-∞,4)

• (4,∞)

What is the domain of the function shown below?

• (-2,5)

• (0,12)

• All Real Numbers

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, that is decaying can be modeled by                      f(x) = 800(.87)^x, where x is the number of days since the decay started. By what percentage is the colony decaying?

• 87%
• 13%
• 800%
• 8.7%

The amount of ants in a colony, f, 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 amount of downloads for an album on iTunes, g(d), where d is the number of days since the album was first uploaded can be represented as
g(d) = 5^1.5d
How many downloads will the album have after 3 days?

• 125
• 11
• 1398
• 140