AnswersFL-1200330-Algebra 2 CRRewriting Exponential Functions

Rewriting Exponential Functions Answers

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5

Choose the pair of expressions that describe the accounts y years after Martin opened his account.

A
Martin: 200(1.05)y Cary: 200(1.05)y+4
B
Martin: 200(1.05)y+4 Cary: 200(1.05)y–4
C
Martin: 200(0.05)y Cary: 200(0.05)y–4
D
Martin: 200(1.05)y Cary: 200(1.05)y–4
6

Which expression represents the mass of sodium remaining after h half-lives?

A
S = 0.5(800)h
B
S = 800(0.5)h
C
S = 8000.5h
D
S = 800h + 0.5
7

Is this exponential growth or decay? Explain using your understanding of the properties of exponents. (To type exponents, use the ^ key.)

Answer:

This is exponential decay. The property of negative exponents states that a^(-n) = 1/a^n, so 2^(-t/8) can be rewritten as (1/2)^(t/8) or 0.5^(t/8). Because the base (0.5) is between 0 and 1, the function represents decay.

8

What is the half-life for the zombie population? Explain in terms of exponents. (To type an exponent, use the ^ key.)

Answer:

To find the half-life, the exponential part of the function (0.5)^(t/8) needs to equal 0.5. This happens when the exponent t/8 equals 1. Solving for t, we get t = 8. Therefore, the half-life is 8 units of time (such as hours or days), because at t = 8, the base of 0.5 is raised to the power of 1, resulting in half of the initial population.

12

Check all facts you included in your answer.

A
The negative exponent means that you must take the reciprocal of the base 2.
B
The reciprocal of 2 is 0.5 (or ½).
C
The base 0.5 (or ½) is less than 1.
D
Bases less than 1 cause decay.
13

Check all facts you included in your answer.

A
The exponential part of the expression needs to be equal to ½, or 0.5.
B
The half-life time will occur at the value of t that gives an exponent of 1.
C
The value t = 8 causes the exponent to be 1, so that’s the half-life.

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