Precalculus : Introductory Calculus

Study concepts, example questions & explanations for Precalculus

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Example Questions

Example Question #41 : Introductory Calculus

Find the following limit:

Possible Answers:

Correct answer:

Explanation:

To solve, simply realize you are dealing with a limit whose numerator and demominator have the same max power. Thus the limit is simply the division of their coefficient.

Example Question #1 : Determine If A Function Is Continuous Using Limits

Find the domain where the following function is continuous:

Possible Answers:

Correct answer:

Explanation:

The function in the numerator factors to:

so if we cancel the x+3 in the numerator and denominator we have the same function but it is continuous. The  gives us a hole at x=-3 so our function is not continuous at x=-3. 

Example Question #1 : Determine If A Function Is Continuous Using Limits

What are the discontinuities in the following function and what are their types?

Possible Answers:

Correct answer:

Explanation:

Since the factor  is in the numerator and the denominator, there is a removable discontinuity at .  The function is not defined at , but function would move towards the same point for the resultant function .

Since the factor cannot be factored out, there is an infinite discontinuity at  .  The denominator will get very small and the numerator will move toward a fixed value.

There is no discontinuity at all at .  The function simply evaluates to zero at this point.

Example Question #662 : Pre Calculus

Determine if the function  is continuous at  using limits.

Possible Answers:

No, it is not continuous because the lefthand and righthand limits do not equal the value of the function at 0. 

Yes, it is continuous because the lefthand and righthand limits are equal.

Yes, it is continuous because the righthand and lefthand limits are equal to the actual value of the function. 

No, it is not continuous because the lefthand limit does not match the righthand limit.

Correct answer:

Yes, it is continuous because the righthand and lefthand limits are equal to the actual value of the function. 

Explanation:

In order to determine if a function is continuous at a point three things must happen.

1) Taking the limit from the lefthand side of the function towards a specific point exists.

2) Taking the limit from the righthand side of the function towards a specific point exists.

3) The limits from 1) and 2) are equal and equal the value of the original function at the specific point in question.

In our case,

1) 

2)  

3) 

Because all of these conditions are met, the function is continuous at 0. 

Example Question #1 : Determine If A Function Is Continuous Using Limits

Determine if  is continuous on all points of its domain.

Possible Answers:

No, it is not continuous because the lefthand and righthand limits do not equal the value of the function at 0.

No, it is not continuous because the lefthand limit does not match the righthand limit.

Yes, it is continuous because the lefthand and righthand limits are equal.

Yes, it is continuous because the righthand and lefthand limits are equal to the actual values of the function. 

Correct answer:

Yes, it is continuous because the righthand and lefthand limits are equal to the actual values of the function. 

Explanation:

First, find that at any point where .

Then find that 

 and .

As these are all equal, it can be determined that the function is continuous on all points of its domain.

Example Question #5 : Determine If A Function Is Continuous Using Limits

Let . Determine if the function is continuous using limits. 

Possible Answers:

Correct answer:

Explanation:

As  approaches , the function  approaches , which is undefined. However, if we factor , we get:

The  factors in the numerator and denominator cancel out, leaving .

Therefore, our function is continuous at all values of  from .

Example Question #1 : Rate Of Change Problems

Find the average rate of change of the function  over the interval from  to .

Possible Answers:

Correct answer:

Explanation:

The average rate of change will be found by .

Here, , and .

Now, we have .

Example Question #2 : Rate Of Change Problems

Let a function be defined by .

Find the average rate of change of the function over .

Possible Answers:

Correct answer:

Explanation:

We use the average rate of change formula, which gives us .

Now , and .

Therefore, the answer becomes .

Example Question #2 : Derivatives

Suppose we can model the profit, , in dollars from selling  items with the equation .

Find the average rate of change of the profit from  to .

Possible Answers:

Correct answer:

Explanation:

We need to apply the formula for the average rate of change to our profit equation. Thus we find the average rate of change is .

Since , and , we find that the average rate of change is .

Example Question #3 : Derivatives

Let the profit, , (in thousands of dollars) earned from producing  items be found by .

Find the average rate of change in profit when production increases from 4 items to 5 items.

Possible Answers:

Correct answer:

Explanation:

Since , we see that this equals. Now let's examine  which simplifies to .

Therefore the average rate of change formula gives us .

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