A+ Answers


Question 1          

Solve the following exponential equation by expressing each side as a power of the same base and then equating exponents.

31-x = 1/27

A. {2}     

B. {-7}   

C. {4}    

D. {3}     

Question 2          

Write the following equation in its equivalent exponential form.



5 = logb 32

A. b5 = 32            

B. y5 = 32            

C. Blog5 = 32        

D. Logb = 32        

Question 3          

Use properties of logarithms to expand the following logarithmic expression as much as possible.



Logb (√xy/ z3)

A. 1/2 logx - 6 logy + 3 logz     

B. 1/2 logb x - 9 logb y - 3 logb z     

C. 1/2 logb x + 3 logb y + 6 logb z   

D. 1/2 logb x + 3 logb y - 3 logb z     

Question 4          

Solve the following exponential equation. Express the solution set in terms of natural logarithms or common logarithms to a decimal approximation, of two decimal places, for the solution.

32x + 3x - 2 = 0

A. {1}     

B. {-2}   

C. {5}    

D. {0}     

Question 5          

Write the following equation in its equivalent logarithmic form.

3√8 = 2

A. Log2 3 = 1/8   

B. Log8 2 = 1/3   

C. Log2 8 = 1/2   

D. Log3 2 = 1/8    

Question 6          

Solve the following exponential equation. Express the solution set in terms of natural logarithms or common logarithms to a decimal approximation, of two decimal places, for the solution.

ex = 5.7

A. {ln 5.7}; ≈1.74

B. {ln 8.7}; ≈3.74

C. {ln 6.9}; ≈2.49

D. {ln 8.9}; ≈3.97 

Question 7          

Write the following equation in its equivalent exponential form.



log6 216 = y

A. 6y = 216          

B. 6x = 216          

C. 6logy = 224      

D. 6xy = 232         

Question 8          

Use properties of logarithms to expand the following logarithmic expression as much as possible.

logb (x2y)

A. 2 logx + logy             

B. 2 logx + logy            

C. logx - logy    

D. logx – logy  

Question 9          

An artifact originally had 16 grams of carbon-14 present. The decay model A = 16e -0.000121t describes the amount of carbon-14 present after t years. How many grams of carbon-14 will be present in 5715 years?

A. Approximately 7 grams              

B. Approximately 8 grams              

C. Approximately 23 grams           

D. Approximately 4 grams              

Question 10        

Solve the following logarithmic equation. Be sure to reject any value of x that is not in the domain of the original logarithmic expressions. Give the exact answer. Then, where necessary, use a calculator to obtain a decimal approximation, to two decimal places, for the solution.

2 log x = log 25

A. {12}  

B. {5}     

C. {-3}   

D. {25}   

Question 11        

Evaluate the following expression without using a calculator.

Log7 √7

A. 1/4    

B. 3/5    

C. 1/2    

D. 2/7     

Question 12        

Write the following equation in its equivalent logarithmic form.

2-4 = 1/16

A. Log4 1/16 = 64              

B. Log2 1/24 = -4

C. Log2 1/16 = -4              

D. Log4 1/16 = 54              

Question 13        

Use properties of logarithms to condense the following logarithmic expression. Write the expression as a single logarithm whose coefficient is 1.

log2 96 – log2 3

A. 5       

B. 7       

C. 12     

D. 4        

Question 14        

The half-life of the radioactive element krypton-91 is 10 seconds. If 16 grams of krypton-91 are initially present, how many grams are present after 10 seconds? 20 seconds?

A. 10 grams after 10 seconds; 6 grams after 20 seconds     

B. 12 grams after 10 seconds; 7 grams after 20 seconds     

C. 4 grams after 10 seconds; 1 gram after 20 seconds         

D. 8 grams after 10 seconds; 4 grams after 20 seconds        

Question 15        

Use properties of logarithms to condense the following logarithmic expression. Write the expression as a single logarithm whose coefficient is 1.

log x + 3 log y

A. log (xy)           

B. log (xy3)          

C. log (xy2)          

D. logy (xy)3         

Question 16        

Write the following equation in its equivalent exponential form.



4 = log2 16

A. 2 log4 = 16     

B. 22 = 4              

C. 44 = 256         

D. 24 = 16             

Question 17        

Approximate the following using a calculator; round your answer to three decimal places.

3√5

A. .765  

B. 14297             

C. 11.494            

D. 11.665             

Question 18        

Approximate the following using a calculator; round your answer to three decimal places.

e-0.95

A. .483  

B. 1.287              

C. .597 

D. .387  

Question 19        

The exponential function f with base b is defined by f(x) = __________, b > 0 and b ≠ 1. Using interval notation, the domain of this function is __________ and the range is __________.

A. bx; (∞, -∞); (1, ∞)          

B. bx; (-∞, -∞); (2, ∞)         

C. bx; (-∞, ∞); (0, ∞)          

D. bx; (-∞, -∞); (-1, ∞)         

Question 20        

Find the domain of following logarithmic function.

f(x) = log5 (x + 4)

A. (-4, ∞)              

B. (-5, -∞)            

C. (7, -∞)             

D. (-9, ∞)