Algebra II : Log-Base-10

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #1 : Logarithms

Based on the definition of logarithms, what is  ? 

Possible Answers:

10

2

4

100

3

Correct answer:

3

Explanation:

For any equation , . Thus, we are trying to determine what power of 10 is 1000. , so our answer is 3. 

Example Question #1 : Log Base 10

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Take the common logarithm of both sides, and take advantage of the property of the logarithm of a power:

Example Question #1 : Log Base 10

What is the value of ?

Possible Answers:

Correct answer:

Explanation:

Base-10 logarithms are very easy if the operands are a power of .  Begin by rewriting the question:

Becomes...

because 

Applying logarithm rules, you can factor out the :

Now,  is .

Therefore, your answer is .

Example Question #1 : Log Base 10

What is the value of ?

Round to the nearest hundreth.

Possible Answers:

Correct answer:

Explanation:

Base-10 logarithms are very easy if the operands are a power of .  Begin by rewriting the question:

Becomes...

because 

Applying logarithm rules, you can factor out the :

Now,  is .

Therefore, your answer is .

Example Question #1 : Log Base 10

Many textbooks use the following convention for logarithms: 

What is the value of ?

Possible Answers:

Correct answer:

Explanation:

Remember:

 is the same as saying .

So when we ask "What is the value of ?", all we're asking is "10 raised to which power equals 1,000?" Or, in an expression: 

.

From this, it should be easy to see that .

Example Question #1 : Log Base 10

Evaluate the following expression:

 

Possible Answers:

Correct answer:

Explanation:

Without a subscript a logarithmic expression is base 10.

The expression  

The logarithmic expression is asking 10 raised to what power equals 1000 or what is x when

We know that

so 

Example Question #7 : Log Base 10

Assuming the value of  is positive, simplify:  

Possible Answers:

Correct answer:

Explanation:

Rewrite the logarithm in division.

As a log property, we can pull down the exponent of the power in front as the coefficient.

Cancel out the .

The answer is:  

Example Question #8 : Log Base 10

Solve the following:

Possible Answers:

Correct answer:

Explanation:

When the base isn't explicitly defined, the log is base 10. For our problem, the first term

is asking:

For the second term,

is asking:

So, our final answer is

 

 

Example Question #2 : Log Base 10

Which of the following expressions is equivalent to the expression  ?

Possible Answers:

None of the other choices is correct.

Correct answer:

Explanation:

By the reverse-FOIL method, we factor the polynomial as follows:

 

Therefore, we can use the property 

as follows:

Example Question #4 : Log Base 10

Evaluate .

Possible Answers:

Correct answer:

Explanation:

The first thing we can do is bring the exponent out of the log, to the front:

Next, we evaluate :

Recall that log without a specified base is base 10 thus 

.

Therefore

becomes,

.

Finally, we do the simple multiplication:

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