AP Calculus AB : Limits of Functions (including one-sided limits)

Study concepts, example questions & explanations for AP Calculus AB

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Example Questions

Example Question #13 : Understanding The Limiting Process.

Find the derivative of: 

Possible Answers:

Correct answer:

Explanation:

This problem involves the chain rule for derivatives. However, you must first rewrite the function as:

  or .

Then, apply the chain rule (first multiply the exponent by the coefficient in front of the binomial [1], then decrease the exponent of the binomial by 1, and finally take the derivative of the binomial):

When simplifiying, change negative exponents to positive ones. Therefore, the answer is:

.

Example Question #15 : Understanding The Limiting Process.

If , then  

Possible Answers:


 

Correct answer:


Explanation:

The correct answer is .

We must use the product rule to solve. Remember that the derivative of  is .

 

 

Example Question #51 : Limits Of Functions (Including One Sided Limits)

Differentiate .

Possible Answers:

Correct answer:

Explanation:

The derivative of  is equal to  therefore the first part of the equation remains the same.

The second part requires regular differential rules.

Therefore when differentiating  you get .

Combining the first and second part we get the final derivative:

.

Example Question #52 : Limits Of Functions (Including One Sided Limits)

Evaluate:

 .

Possible Answers:

Correct answer:

Explanation:

The derivative of  is .

Therefore the integral of

 where C is some constant.

Example Question #52 : Limits Of Functions (Including One Sided Limits)

Differentiate .

Possible Answers:

Correct answer:

Explanation:

The rule for taking the derivative of .

For this problem we need to remember to use the Chain Rule.

Since we are taking the derivative of,

  we need to take the derivative of the outside piece  keeping the inside piece the same , and then multiply the whole thing by the derivative of the inside piece .

Therefore the solution becomes:

,

.

 

Example Question #53 : Limits Of Functions (Including One Sided Limits)

If  what is ?

Possible Answers:

Correct answer:

Explanation:

The derivative of,

.

The derivative of 

Therefore, using the Chain Rule the derivative of the function will become the derivative of the outside piece keeping the original inside piece. Then multiplying that by the derivative of the inside piece.

 

Example Question #16 : Understanding The Limiting Process.

Evaluate the following limit:

Possible Answers:

does not exist

Correct answer:

Explanation:

  Recall the formal definition of the derivative:

 

When you evaluate this limit the output is f'(x). In this question f(x) = ln(x) so what this question is really saying is take the derivative of f(x) and evaluate it at 2.  

Take the derivative:

Substitute the value 2 into the derivative:

 

Example Question #53 : Limits Of Functions (Including One Sided Limits)

Evaluate the following limit:

Possible Answers:

Correct answer:

Explanation:

This limit is very simple(almost too simple) because it asks for the limit at a location where there is no discontinuity. Fortunately, this makes taking the limit trivial.

Substitute x=4 into the function to evaluate the limit.

Example Question #18 : Understanding The Limiting Process.

Evaluate the following limit:

Possible Answers:

Correct answer:

Explanation:

As x becomes infinitely large, the x terms with the highest power dominate the function and the terms of lower order become negligible.  This means that near infinity, the x^5 term in the numerator and the 10X^5 term in the denominator are the only values necessary to evaluate the limit.

Simplify and evaluate:

Example Question #19 : Understanding The Limiting Process.

Evaluate the following limit:

Possible Answers:

does not exist

Correct answer:

does not exist

Explanation:

First, factor x-2 out from the numerator and denominator.

At x=4 there is a discontinuity, so we must evaluate the limit from the right and left side to see if it exists.

Evaluated from the right:

From the left:

 

Because the limit from the right is not equal to the limit from the left, the function does not exist at x=4.

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