Writing and interpreting exponential functions

The value of a car is $15,000 and depreciates at a rate of 8% per year. What is the exponential equation?

• y=8(15,000)^x
• y=15,000(1.08)^x

• y=15,000(0.92)^x

• y=15,000(0.08)^x

 A flea medicine breaks down at a decay rate of 20% per hour.  The initial dose is 60 milligrams. Which of the following represent the equation the models the amount of flea medicine left in an animal, x hours after it was given?

What is the explicit rule for the sequence:
4, 12, 36, ...

• a_n = 4/3(3)ⁿ
• a_n = 4x3
• a_n = 2(3)ⁿ

Which describes what is happening to Amazon's stock?

• The stock price starts at $50 and quadruples each year.

• The stock price starts at $50 and adds by $150 each year

• The stock price is increasing at a constant rate of $250 per year.

• The stock price is staying the same each year.

Florine-21 has a half-life of 4 seconds. You begin with a 50 mg sample of Florine-21.

Which exponential equation would represent the amount of Florine-21after t seconds.

If a Costco blueberry muffin is left on the counter, mold spores will begin to grow. On Saturday there were 2 mold spores that begin to triple each day. Which equation represents the growth of mold after x days?

What is the form of an exponential function?

Suppose a culture of bacteria begins with 5000 cells and dies by 30% each year. Write an equation that represents this situation.

• y=5000(1 - .30)^x
• y=30(1- 5000)^x
• y=5000(1 + .30)^x
• y=5000x^x

Suppose the population of a species of insects doubles every year. There are 1600 insects initially. The function for the scenario would be?

• $f\left(x\right)=2x+1600$

• $f\left(x\right)=1600\times2$

• $f\left(x\right)=1600\cdot2^x$

Which shows using the point (1, 1), initial amount = 2, and horizontal asymptote = -4 correctly to find b?