Algebra II : Logarithms

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #28 : Solving Logarithms

Evaluate .

Possible Answers:

Correct answer:

Explanation:

We can take this problem and expand it a bit, which will make things easier in the long run.  We know that:

Using one of our logarithmic properties, we can expand even further:

Another log property states that:

So:

Example Question #21 : Solving And Graphing Logarithms

Solve:

Possible Answers:

Correct answer:

Explanation:

To solve for x, remember that exponents inside logarithms can be moved to the front of the logarithm:

Next, we can rewrite the logarithm as the number it equals, and solve for x:

Example Question #22 : Solving And Graphing Logarithms

Solve:  

Possible Answers:

Correct answer:

Explanation:

In order to solve for the x-variable, we will need to exponential function both sides of the equation in order to eliminate the natural log.

The equation becomes:

Divide by two on both sides.

The answer is:  

Example Question #3071 : Algebra Ii

Expand the log:  

Possible Answers:

Correct answer:

Explanation:

Rewrite the logarithm using the quotient property.

Rewrite the log.

Use the power property to pull down the power.

Simplify the log terms.

The answer is:  

Example Question #3072 : Algebra Ii

Solve for :

Possible Answers:

None of these

Correct answer:

Explanation:

Using definition of logarithms:

Example Question #3073 : Algebra Ii

Solve for :

Possible Answers:

None of these

Correct answer:

Explanation:

Using definition of logarithms

Example Question #31 : Solving And Graphing Logarithms

Solve the following equation:

Possible Answers:

Correct answer:

Explanation:

Recall the definition of a logarithm. For a logarithm in any base 

denotes

.

In other words, the value of a logarithm is simply an exponent, and it is defined at  whenever the base can be raised to a sufficient power to yield . Hence, the equation

may be rewritten as

 .

Raising  to the th power yields , and so

.

Example Question #32 : Solving Logarithms

Solve the following equation:

Possible Answers:

Correct answer:

Explanation:

According to the rule for multiplying logarithms,  for any constant value . In other words, an exponent on the quantity inside a logarithm can be moved outside the logarithm as a multiplier, and vice versa. Hence,

.

Since the natural logarithm has  as its base, the definition of logarithms applies in this case:  whenever the base of  is equal to .

.

This implies that  and . However, substituting the solution  into the original equation yields the following expression:

which is not defined, since logarithms are undefined for any value of .

Hence, we eliminate the extraneous solution  and submit that the correct solution to this equation is .

 

Example Question #33 : Solving Logarithms

Solve for :   

Possible Answers:

Correct answer:

Explanation:

Use the following interchangeable properties to solve for the unknown variable:

For the equation , this would be equivalent to:  

Divide by two on both sides and convert the negative exponent to a fraction.

The answer is:  

Example Question #34 : Solving Logarithms

Solve the log:  

Possible Answers:

Correct answer:

Explanation:

In order to simplify this log, we will need to convert the nine to base three.

Rewrite the term inside the log.

Rewrite this as a fraction.

According to log rules, we can pull the power of the inner quantity inside the log out as the coefficient.

The answer is:  

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