Precalculus : Pre-Calculus

Study concepts, example questions & explanations for Precalculus

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Example Questions

Example Question #4 : Determine If A Relation Is A Function

Is the following relation of ordered pairs a function? 

 

 

Possible Answers:

Yes

No

Cannot be determined

Correct answer:

Yes

Explanation:

A set of ordered pairs is a function if it passes the vertical line test.

Because there are no more than one corresponding  value for any given  value, the relation of ordered pairs IS a function.

Example Question #1 : Real Numbers

Which of the following is not true about a field. (Note: the real numbers  is a field)

Possible Answers:

A field can be defined in many ways.

For every element  in the field, there is another element  such that their product   is equal to , where  is the multiplicative identity,  in the case of real numbers.

There is an element  in the field such that  for any element  in the field.

We have  for any  and  in the field.

For every element  in the field, there is another element  such that their sum  is equal to , where  is the additive identity. 

Correct answer:

For every element  in the field, there is another element  such that their product   is equal to , where  is the multiplicative identity,  in the case of real numbers.

Explanation:

It is not the case that for any element  in a field, there is another one  such that their product is . Take  in the real numbers. Multiply  by any number and you get , so you will never get . This is true for any field that has more than 1 element.

Example Question #1 : Modeling

John lives in Atlanta, but commutes every Monday to LaGrange where he has an apartment he stays in Monday-Friday for work. Each Monday he drives 350 miles to LaGrange. Once he arrives to his home away from home he is in walking distance of work and does not use his car for anything else. After 23 weeks his odometer shows 186,000 miles. Write an equation that models his odometer reading as a function of the number of weeks he has been driving after commencing his new job.

Possible Answers:

Correct answer:

Explanation:

The rate of change of his mileage is 700 per week (350 x 2=700 there and back). The rate of change is the same thing as slope. Since we are looking for equation an equation that models his odometer reading as a function of the number of weeks he has been driving we can extract the point (23 , 18600) since after 23 weeks his odometer read 18,600 miles. Now we will use the point slope formula:

distribute the right side

isolate y

 

 

Example Question #1 : Linear Modeling

John lives in Atlanta, but commutes every Monday to LaGrange where he has an apartment he stays in Monday-Friday. Each Monday he drives 350 miles to LaGrange. Once he arrives to his apartment he is in walking distance of work and does not use his car for anything else. After 23 weeks his odometer shows 186,000 miles. Write an equation that models his odometer reading as a function of the number of weeks he has been driving after commencing his new job. Using the equation you just made, what is the y intercept or his original mileage before starting?

Possible Answers:

y intercept=16,100 miles

y intercept=186,000 miles

y intercept=153,800 miles

y intercept=169,900 miles

Need more information to solve.

Correct answer:

y intercept=169,900 miles

Explanation:

The y intercept can be found by plugging in 0 for x in your original equation: y=700x+169,900 because at x=0 you can only reach the y axis and thus will find the y intercept. 

Example Question #1 : Inverse Functions

What is the inverse function of

 ?

Possible Answers:

Correct answer:

Explanation:

To find the inverse function of

we replace the  with  and vice versa.

So

Now solve for 

Example Question #2 : Find The Inverse Of A Relation

Find the inverse of the function.

 

Possible Answers:

Correct answer:

Explanation:

To find the inverse function, first replace  with :

Now replace each  with an  and each  with a :

Solve the above equation for :

Replace  with . This is the inverse function:

 

 

Example Question #3 : Inverses

Find the inverse of the function.

 

Possible Answers:

Correct answer:

Explanation:

To find the inverse function, first replace  with :

Now replace each  with an  and each  with a :

Solve the above equation for :

Replace  with . This is the inverse function:

Example Question #3 : Find The Inverse Of A Relation

Find the inverse of the function .

Possible Answers:

Correct answer:

Explanation:

To find the inverse of , interchange the  and  terms and solve for .

Example Question #1031 : Pre Calculus

What point is the inverse of the ?

Possible Answers:

Correct answer:

Explanation:

When trying to find the inverse of a point, switch the x and y values.

So  

Example Question #1032 : Pre Calculus

What is the inverse of ?

Possible Answers:

Correct answer:

Explanation:

When trying to find the inverse of a point, switch the x and y values.

So, 

 
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