SAT II Math I : SAT Subject Test in Math I

Study concepts, example questions & explanations for SAT II Math I

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Example Questions

Example Question #12 : Range And Domain

What is the domain of the function?

Possible Answers:

Correct answer:

Explanation:

There are two limitations in the function: the radical and the denominator term. A radical cannot have a negative term, and a denominator cannot be equal to zero. Based on the first restriction (the radical), our  term must be greater than or equal to zero. Based on the second restriction (the denominator), our  term cannot be equal to 4. Our final answer will be the union of these two sets.

Minimum: 0 (inclusive), maximum: infinity

Exclusion: 4

Domain: 

Example Question #12 : Range And Domain

What is the domain of the following function? Please use interval notation.

Possible Answers:

Correct answer:

Explanation:

A basic knowledge of absolute value and its functions is valuable for this problem. However, if you do not know what the typical shape of an absoluate value function looks like, one can always plug in  values and plot points.

Upon doing so, we learn that the -values (domain) are not restricted on either end of the function, creating a domain of negative infinity to postive infinity.

If we plug in -100000 for , we get 100000 for

If we plug in 100000 for , we get 100000 for .

Additionally, if we plug in any value for , we will see that we always get a real, defined value for .

 

**Extra Note: Due to the absolute value notation, the negative (-) next to the  is not important, in that it will always be made positive by the absolute value, making this function the same as  .  If the negative (-) was outside of the absolute value, this would flip the function, making all corresponding -values negative. However, this knowledge is most important for range, rather than domain.

Example Question #11 : Domain And Range

Use the following function and domain to answer this question

Find the range of the function for the given doman.  Are  and  directly or inversely related?

Possible Answers:

Correct answer:

Explanation:

To find the range, plug each value of the domain into the equation:

As the x-values increase, the y-values do as well.  Therefore there is a  relationship

 

Example Question #14 : Domain And Range

Find the range of the function  for the domain .

Possible Answers:

Correct answer:

Explanation:

The range of a function is the group of corresponding  values for a given domain ( values).  Plug each  value into the function to find the range:

The range is .

Example Question #11 : Domain And Range

A function has the following range:

Which of the following CANNOT be the domain of the function.

Possible Answers:

Correct answer:

Explanation:

Functions cannot have more than one  value for each value.  This means different numbers in the range cannot be assigned to the same value in the domain.  Therefore, cannot be the domain of the function.

Example Question #41 : Introduction To Functions

What is the range of the following function? Please use interval notation.

Possible Answers:

Correct answer:

Explanation:

A basic knowledge of absolute value and its functions is valuable for this problem. However, if you do not know what the typical shape of an absoluate value function looks like, one can always plug in  values and plot points.

Upon doing so, we learn that the -values (range) never surpass . This is because of the negative that is placed outside of the absolute value function. Meaning, for every  value we plug in, we will always get a negative value for , except when .

With this knowledge, we can now confidently state the range as 

 

**Extra note: the negative sign outside of the absolute value is simply a transformation of , reflecting the function about the -axis. 

Example Question #11 : Functions And Graphs

Find the domain of the function; express the domain in set builder notation, 

 

Possible Answers:

 (all real numbers)

Correct answer:

Explanation:

 Finding the Domain

The domain of a function is the set of all  over which the function  is defined. 

 When adding functions the domain is the intersection between the domains of the two functions. In our case we will consider  to be the sum of two funcitons  and . The domain of  is simply all real numbers , so the domain of  will be whatever the domain of  . 

 

The domain of  can be found by remembering that everything under the radicand must be either a postive real number or zero. Apply this condition, 

 

So the domain is, 

 

 

 

 

 Plot problem 9

Here we can see graphically what happens when we add the fucntions. The red line is , and the green curve is  . The blue line is the sum of these two fucntions , and has the same domain as the function in green which starts at , and continues for all real numbers greater than .  

Example Question #21 : Functions And Graphs

Find the domain and range of the function . Express the domain and range in interval notation.

 

Possible Answers:

Domain

Range

Domain

 

Range

  (all real numbers) 

Domain

Range

 

Domain

 

Range 

Domain

 (all real numbers) 

Range

Correct answer:

Domain

 

Range 

Explanation:

 

Finding the Domain


The domain of a function is defined as the set of all valid input values of  overwhich the function is defined. The simple rule of thumb for rational functions is that all real numbers will work except for those in which denominator is zero since division by zero is not allowed.

Set the denominator to zero and solve for 

 

The function is therefore defined everywhere except at . Therefore the domain expressed in interval notation is,

Note that the open parentheses indicate that  is not in the domain, but  may become arbitrarily close to  . 

Finding the Range 

The range of a function is defined as the set of all outputs spanning the domain. Finding the range can be achieved by finding the domain of the inverse function. First solve   for  to obtain the inverse function, 

 

 

Multiply both sides by 

 

Distribute 

 

Move all terms with  to one side of the equation, 

 

Factor and solve for 

 

The inverse function is therefore,

 

Find the domain of the inverse function, 

 

The range of  is the domain of , which is:

 

If you look at the plots for the function  (in blue) and  (in red and labeled as  in the figure) you can see the asymptotic behavior of as  approaches  and of  as  approaches .

 

Problem 1 plot2

 

 

Example Question #22 : Properties Of Functions And Graphs

Determine the domain for the function given:

Possible Answers:

Correct answer:

Explanation:

To determine the domain of the function, we must ask ourselves where x can and cannot exist. On the numerator, nothing is preventing x from existing anywhere. But the denominator of the function cannot equal zero (which would produce an undefined value for the function), so to determine at which x values this occurs, we must set the denominator equal to zero and solve for x:

(The factors of 6 that add up to 5 are 3 and 2.)

Because these are the only values that x equal for the function to exist, we make our intervals as shown below:

We use round brackets to indicate that we never include the bounds of the intervals in the domain.

Example Question #23 : Properties Of Functions And Graphs

Find the domain of the function given:

Possible Answers:

Correct answer:

Explanation:

To determine the domain of the function, we must consider where x cannot exist. The only limitation on the function is the denominator, which cannot equal zero. 

To find the x-values where this occurs, we must set the denominator equal to zero and solve for x:

These are the only two limitations on the domain of the function, so the domain of the function is

Note that round brackets were used for all of the intervals, because none of the bounds of the intervals are included in the domain.

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