Calculus AB : Implicit Differentiation and Chain Rule

Study concepts, example questions & explanations for Calculus AB

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Example Questions

Example Question #71 : Differentiating Functions

Differentiate, 

Possible Answers:

Correct answer:

Explanation:

                          (1) 

An easier way to think about this:

Because  is a function of a function, we must apply the chain rule. This can be confusing at times especially for function like equation (1). The differentiation is easier to follow if you use a substitution for the inner function, 

Let,

                               (2)

So now equation (1) is simply, 

                               (3)

Note that  is a function of . We must apply the chain rule to find  

                            (4)

 To find the derivatives on the right side of equation (4), differentiate equation (3) with respect to , then Differentiate equation (2) with respect to 

                   

Substitute into equation (4),  

                  (5)

Now use  to write equation (5) in terms of  alone: 

Example Question #71 : Differentiating Functions

Find  given 

Possible Answers:

Correct answer:

Explanation:

Here we use the chain rule: 

Let 

Then 

And 

Example Question #71 : Differentiating Functions

If  , find the derivative through implicit differentiation.

Possible Answers:

Correct answer:

Explanation:

To find the derivative through implicit differentiation, we have to take the derivative of every term with respect to x.  Don't forget that each time you take the derivative of a term containing y, you must multiply its derivative by y'.  So, when we take the derivative of each term, we get   The next step is to solve for y', so we put all terms containing y' on the left side of the equation: .  Next, factor out the y' from both terms on the left side of the equation so that we can solve for it:   To get y' alone, divide both sides by  to get .  To simplify even further, we can factor a 2 out of the numerator and denominator and cancel them.  So, the final answer is .

Example Question #72 : Differentiating Functions

Use the chain rule to find the derivative of the function 

Possible Answers:

Correct answer:

Explanation:

First, differentiate the outside of the parenthesis, keeping what is inside the same.

You should get  .

Next, differentiate the inside of the parenthesis. 

You should get .

Multiply these two to get the final derivative .

Example Question #81 : Differentiating Functions

Find the derivative of the following function:

.

Possible Answers:

Correct answer:

Explanation:

This is a chain rule derivative.  We must first differentiate the natural log function, leaving the inner function as is. Recall:

Now, we must replace this with our function, and multiply that by the derivative of the inner function:

Example Question #81 : Differentiating Functions

Find the derivative of .

Possible Answers:

Correct answer:

Explanation:

Use chain rule to solve this. First, take the derivative of what is outside of the parenthesis.

You should get .

Next, take the derivative of what is inside the parenthesis. 

You should get .

Multiplying these two together gives .

Example Question #101 : Differentiating Functions

If , calculate 

Possible Answers:

Correct answer:

Explanation:

Using the chain rule, we have

.

Hence, .

Notice that we could have also simplified  first by cancelling the natural log and the exponential function leaving us with just , thereby avoiding the chain rule altogether.

Example Question #84 : Differentiating Functions

Use implicit differentiation to find  is terms of  and  for,  

Possible Answers:

Correct answer:

Explanation:

To differentiate the equation above, start by applying the derivative operation to both sides,

Both sides will require the product rule to differentiate,

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 Common Mistake 

A common mistake in the previous step would be to conclude that  instead of  . The former is not correct; if we were looking for the derivative with respect to , then  would in fact be . But we are not differentiating with respect to , we're looking for the derivative with respect to .

We are assuming that  is a function of , so we must apply the chain rule by differentiating with respect to  and multiplying by the derivative of  with respect to  to obtain .

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Collect terms with a derivative onto one side of the equation, factor out the derivative, and divide out  to solve for the derivative 

Therefore, 

Example Question #101 : Differentiating Functions

Find the derivative of .

Possible Answers:

Correct answer:

Explanation:

This is a chain rule derivative.  We must first start by taking the derivative of the outermost function.  Here, that is a function raised to the fifth power.  We need to take that derivative (using the power rule).  Then, we multiply by the derivative of the innermost function:

Example Question #83 : Differentiating Functions

Find the derivative of the function: .

Possible Answers:

Correct answer:

Explanation:

Whenever we have an exponential function with , the first term of our derivative will be that term repeated, without changing anything.  So, the first factor of the derivative will be .  Next, we use chain rule to take the derivative of the exponent.  Its derivative is .  So, the final answer is .

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