Exponential Functions Summative Review

Is this exponential growth or decay?

• Growth
• Decay

What type of function is f(x)=2(7)^x ?

• Exponential Growth

• Linear

• Exponential Decay

• None of the Abovee

What is the y-intercept of the function?

• 2
• 3
• 1
• -2

Write an equation that models the following situation:
Samantha's hair was known to grow very rapidly. It began at a length of 6 in and grew at a rate of 14% a week.

• y=6(0.14)^x

• y=6(1+14)^x

• y=6(1.14)^x

• y=6(0.86)^x

Which of the following functions shows an initial amount of $15 and an increase of 35% each year?

• y = 15(35)^x
• y = 15(1.35)^x
• y = 15(0.35)^x
• y = 35(1.15)^x

Identify the y-intercept (initial value) in the function f(x)=13(.27)^x

• (.27)^x
• .27
• 13
• 3.51

Identify the y-intercept (initial value) of the function f(x)=2(4)^x.

• 2
• 4
• (2)^x
• 8

The value of a car is $15,000 and depreciates at a rate of 8% per year. What is the b-value in your function?

• ^.08

• ^1.08

• .92

• 8

Answer explanation

When finding the b-value in decay functions, you need to do 100%-the % that is leaving.

In this problem, you get 100%-8%=92%.

Then, take that 92% and make it a decimal --> 0.92.

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

• y=5000(0.7)^x

• y=30(5000)^x

• y=5000(1.3)^x

• y=5000x^x

The number of mosquitoes at the beginning of the summer was 4,000. The population of mosquitoes is expected to grow at a rate of 25% a month. How many mosquitoes will there be after 4 months?

• 9766

• 9006

• 9765

• 5433