Calculus 3 : Partial Derivatives

Study concepts, example questions & explanations for Calculus 3

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Example Questions

Example Question #1340 : Calculus 3

Find  if  and .

Possible Answers:

Correct answer:

Explanation:

Find  if  and .

Keep in mind, when taking the derivative with respect to  is treated as a constant, and when taking the derivative with respect to  is treated as a constant.

 

 

To put  solely in terms of  and  , we substitute the definitions of  and   given in the question,   and .

Example Question #1341 : Calculus 3

Find  if  and .

 

Possible Answers:

Correct answer:

Explanation:

Find  if  and .

Keep in mind, when taking the derivative with respect to  is treated as a constant, and when taking the derivative with respect to  is treated as a constant.

 

 

To put  solely in terms of  and  , we substitute the definitions of  and   given in the question,   and .

 

Example Question #1342 : Calculus 3

Find  if  and .

Possible Answers:

Correct answer:

Explanation:

Find  if  and .

Keep in mind, when taking the derivative with respect to  is treated as a constant, and when taking the derivative with respect to  is treated as a constant.

 

 

To put  solely in terms of  and  , we substitute the definitions of  and   given in the question,   and .

 

Example Question #1343 : Calculus 3

Find  if  and .

 

Possible Answers:

Correct answer:

Explanation:

Find  if  and .

Keep in mind, when taking the derivative with respect to  is treated as a constant, and when taking the derivative with respect to  is treated as a constant.

 

 

To put  solely in terms of  and  , we substitute the definitions of  and   given in the question,   and .

 

Example Question #381 : Partial Derivatives

Find  if  and .

 

Possible Answers:

Correct answer:

Explanation:

Find  if  and .

Keep in mind, when taking the derivative with respect to  is treated as a constant, and when taking the derivative with respect to  is treated as a constant.

 

 

To put  solely in terms of  and  , we substitute the definitions of  and   given in the question,   and .

Example Question #1345 : Calculus 3

Find  if  and .

 

Possible Answers:

Correct answer:

Explanation:

Find  if  and .

 

Keep in mind, when taking the derivative with respect to  is treated as a constant, and when taking the derivative with respect to  is treated as a constant.

 

 

To put  solely in terms of  and  , we substitute the definitions of  and   given in the question,   and .

 

Example Question #1346 : Calculus 3

Compute  for the function  where the variables , and  are functions of the of the parameter :

 

Possible Answers:

Correct answer:

Explanation:

Compute  for the function  where the variables , and  are functions of the of the parameter :

Because each function is given in terms of the parameter  we can conveniently write the function as a function of  alone: 

 

Solution 1

For the function described in this problem, the function can be written strictly in terms of the parameter  by simply substituting the definitions given for  or 

                                                          

So now we have the function written in the form of a single variable function of  We can use the usual chain-rule. 

 

Apply the product rule and and the chain-rule:  

                                              

                                                         

 

 

Solution 2

The derivative of  with respect to  will be the sum of the derivatives of each variable , and  with respect to 

 

                                (1) 

 

In Equation (1) we use the partial derivative notation for a derivative of  with respect to the variables , and  since it is a multi-variable function, we have to specify which variable we are differentiating unless we are differentiating with respect to

 

We return to the standard derivative notation when computing the derivatives with respect to  since each function , and  can be written as a single variable function of  Now simply apply (3) to the function term-by-term: 

 

 

 

 

 

Now ad the terms to get an expression for  and then rewrite in terms of 

 

  

 

 

Therefore: 

 

 

 

Example Question #1347 : Calculus 3

Find the two variable function  that satisfies the following:   

 

 

 

 

 

 

 

Possible Answers:

Correct answer:

Explanation:

 

 

 

The first step is to integrate the function with respect to  since that is the outer most derivative in this problem. 

 

 

 

 

Now apply the constraints to compute the two constants of integration. 

 

So far we have: 

Now apply the second constraint given: 

 

 

 

Example Question #382 : Partial Derivatives

Find .

Possible Answers:

Correct answer:

Explanation:

In order to find , we need to take the derivative of  in respect to , and treat , and  as constants. We also need to remember what the derivatives of natural log, exponential functions and power functions are for single variables.

Natural Log:

Exponential Functions:

Power Functions:

 

Example Question #383 : Partial Derivatives

Find .

Possible Answers:

Correct answer:

Explanation:

In order to find , we need to take the derivative of  in respect to  , and treat , and  as constants. We also need to remember what the derivatives of natural log, exponential functions and power functions are for single variables.

Natural Log:

Exponential Functions:

Power Functions:

 

 

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