Algebra II : Domain and Range

Study concepts, example questions & explanations for Algebra II

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Example Questions

Example Question #91 : Domain And Range

Determine the range of:  

Possible Answers:

Correct answer:

Explanation:

The parent function of  looks similar to the  graph and will open upwards.

The negative coefficient in front of the  term indicates that the graph will open downward, which means that the lowest range value is negative infinity.

The y-intercept is 9, an will be the highest point on this graph.

The range is:  

Example Question #92 : Domain And Range

What is the domain?  

Possible Answers:

Correct answer:

Explanation:

Notice that this is a parabolic function that will open downward.  The domain refers to all possible x-values on the graph.  

The parent function  has a domain of all real numbers and a range from .  The transformations of  will not affect the domain, but the range of the graph since the y-values of the graph are affected.

There are no values of the x-variable that will make this function undefined, which means all real numbers can exist.

The answer is:  

Example Question #93 : Domain And Range

Determine the range of:  

Possible Answers:

Correct answer:

Explanation:

Rewrite this in  form.  The equation given is a parabola.

The negative ten coefficient tells us that the parabola will open downward.

The negative three indicates that the y-intercept is at .

Since the curve opens downward, there will be a maximum at the vertex, which is at , since the vertex  is zero as there is no coefficient for .

This means the range will start at negative infinity, and ends at negative three.

The answer is:  

Example Question #94 : Domain And Range

Determine the range of:  

Possible Answers:

Correct answer:

Explanation:

The equation in slope-intercept form, , is:

This is a horizontal line, and the y-value will be fixed at this value, which means the range will not change.  Be careful not to misinterpret  or three as the slope!

The answer is:  

Example Question #95 : Domain And Range

What is the domain of the function f(x) where 

Possible Answers:

None of the other answers

Correct answer:

Explanation:

Recall that the domain of the function f(x) is the set of all x where f(x) is defined. Also, recall that two of the most common ways that a function can be undefined are division by zero and a negative inside of a square root. So, we need to ensure that are domain excludes all x values for which those things can occur. 

The  portion of our equation is of no concern, as the domain of  is all real numbers - that is to say, we can plug any real number into  and it will be defined. However, the  of our equation is cause for concern. We need to avoid two issues here - division by zero, and having a negative in the square root. We know that the only x value that would result in a zero in our denominator is zero, as the square root of zero is zero. That is, if we substitute zero for x, we will have  in our denominator, which evaluates to , leaving a zero in our denominator, leaving us with an undefined function. So, we need to exclude zero from our domain. Secondly, we need to exclude all number below zero from our domain as well, as x values below zero would result in a negative inside of a square root, which would result in an undefined function.

So, summarizing, we need to exclude all numbers below zero as well as zero itself from our domain, resulting in a final answer of: 

Example Question #96 : Domain And Range

Find the domain of the function q(x) where

Possible Answers:

Correct answer:

Explanation:

Recall that the domain of the function q(x) is the set of all x values that result in the function q(x) being defined. In this case, what we need to think about is avoiding a negative number inside of the radical (or square root symbol), which would result in an undefined function. What this means is that we need to all the x values for which the expression inside of the radical is greater than or equal to zero. In mathematical terms, we need to solve for x in the inequality:

Thus, we will have a positive or zero value inside of the radical only when x is less than or equal to -4 and greater than or equal to 4. If we look at the expression inside the radical, this makes sense - for all x values between -4 and 4,  will evaluate to a number less than 16, which will result in a negative inside of the radical and therefore an undefined function. For x values less than or equal to -4 and greater than or equal to 4,  will evaluate to a number greater than or equal to 16, which will result in a positive inside of the radical and therefore a defined function. Written in interval notation, this domain looks like:

Example Question #97 : Domain And Range

What is the range of the function?  

Possible Answers:

Correct answer:

Explanation:

The range of the parent function  is all real numbers.  The coefficient of the x cubed term will widen the curve, and flip the graph since it is a negative value.  The coefficient will not affect the range.

The negative ten at the end will only shift the graph downward 10 units and also will not affect the range of the function.

This means that the range includes all real numbers.

The answer is:  

Example Question #98 : Domain And Range

What is the range of the following function in interval notation?  

Possible Answers:

Correct answer:

Explanation:

The equation given is in the form of .

Since the value of , the location of the vertex  will be at .

Substitute  in order to determine the min or max of this curve.  Since the  coefficient is positive, the parabola will open upward, and will have a minimum.  The  coefficient will not affect the range.

The minimum point is .

The range is including all y-values that are existent on this graph.

The answer is:  

Example Question #99 : Domain And Range

A function  is defined on the domain  according to the following table:

Function

Define a function .

Which of the following values is not in the range of the function ?

Possible Answers:

Correct answer:

Explanation:

This is the composition of two functions. By definition, .  To find the range of , we need to find the values of this function for each value in the domain of . Since , this is equivalent to evaluating  for each value in the range of , as follows:

 

Range value: 3 

 

Range value: 5

 

Range value: 8

 

Range value: 13

 

Range value: 21

 

The range of  on the set of range values of  - and consequently, the range of  - is the set . Of the choices given, only 1 is not in this set.

Example Question #91 : Domain And Range

Find the domain of the rational function, 

 

Possible Answers:

 

 

Correct answer:

Explanation:

 

The domain of a function is the set of all values of the independent variable, , over which the function is defined. The first step is usually to find where the function is undefined. For a rational function this is always going to consist of points where the denominator is zero.

 

Find the roots of the denominator:

 

                                                   (1)

 

This is not one we can easily factor. Therefore, we should use the quadratic formula.

______________________________________________________________

Recall that for a quadratic of the form  the general form of the solution is, 

                                          (2) 

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The solution to equation (1) is, 

 

                                                    (3)

 

The two roots are: 

 

Now that we have the roots for the denominator we can construct the domain using interval notation. Use open parenthesis to exclude the two roots themselves from the domain. Also think of how the roots will split up the number line into three regions. 

 

 

Final number line image

The total domain of our function in interval notation is: 

 

 

 

 

 

 

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