Exponential Functions

What is the equation of the following table?

HINT: Use your STAT Key on your calculator

• y = 7(2)^x

• y = 4x + 7

Rhonda deposited $3000 in an account in the Merrick National Bank, earning 4.2% interest, compounded annually. She made no deposits or withdrawals. Write an equation that can be used to find B, her account balance after t years.

• B(t) = 3000(1 - 4.2)^t

• B(t) = 3000(1 + 4.2)^t

• B(t) = 3000(1 - 0.042)^t

• B(t) = 3000(1 + 0.042)^t

Marilyn collects old dolls. She purchases a doll for $450. Research shows this doll's value will increase by 2.5% each year. Write an equation that determines the value, V, of the doll t years after purchase.

• V(t) = (1 + 0.025)^t

• V(t) = (1 - 0.025)^t

• V(t) = (1 + 2.5)^t

• V(t) = (1 - 2.5)^t

John invested $900 in a savings account at a 2.3% annual interest rate. He made no deposits or withdrawals on the account. Write a function J(t) to represent the amount of money in the account after t years.

• J(t) = 900(1 - 0.23)^t

• J(t) = 900(1 + 0.23)^t

• J(t) = 900(1 + 0.023)^t

• J(t) = 900(1 - 0.023)^t

The rabbit population started at 65,000 rabbits. The population is decreasing at a rate of 1.5% each year. Write a function r(t) to represent the rabbit population after t years.

• r(t) = 65000(1 - 0.015)^t

• r(t) = 65000(1 + 0.015)^t

• r(t) = 65000(1 - 1.5)^t

• r(t) = 65000(1 + 1.5)^t

What represents Growth/Decay on f(x)=a⋅b^x ?

• x

• a

• b

What is the initial value of f(x)= a⋅b^x

• x

• b

• a

The bear population in a given area is currently 1580. They anticipate the bear population to decrease by 2% each year. Which function represents the population of bears, B, after t years.

• B = 1580(0.02)^t

• B = 1580(1 – 0.02)^t

• B = 1580(1 + 0.02)^t

• B = 1580(1 – 0.2)^t

The population of a town is currently 6342 and is increasing by a rate of 1.3% each year. Which function represents the population of people, P, after t years.

• P = 6342(1 + 1.3)^t

• P = 6342(1 – 1.3)^t

• P = 6342(1 + .013)^t

• P = 6342(1 – .013)^t

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

• y = 15(1.035)^x

• y = 15(1.35)^x

• y = 15(0.35)^x

• y = 15(0.65)^x