AP Calculus AB : Computation of the Derivative

Study concepts, example questions & explanations for AP Calculus AB

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Example Questions

Example Question #444 : Ap Calculus Ab

Find the derivative of the following function:

.

Possible Answers:

Correct answer:

Explanation:

Here, we need to take the derivative of a square root function first.  Then, we will multiply that by the derivative of the function under the square root.

Remember:  by another chain rule.

Now, let's make use of our trigonometric identities:

Therefore, we can simplify our answer:

Note, you could have used this trigonometric identity from the very beginning, making the problem much easier!

Example Question #42 : Chain Rule And Implicit Differentiation

Find 

 

Possible Answers:

Correct answer:

Explanation:

For implicit differentiation, we need to take a derivative from left to right of our function.  The only difference is that any time we take the derivative of a  function, we need to explicitly write  after it.  Then, we will use algebra to solve for that 

  Here, just move everything other than the term we want to the right. Then, divide by the coefficient.

Example Question #43 : Chain Rule And Implicit Differentiation

Find  for the following function:

Possible Answers:

Correct answer:

Explanation:

For implicit differentiation, we need to take the derivative of every term, including numbers.  Whenever we take a derivative of a function of , we need to multiply it by .  Then, we will rearrange the equation to solve for

 

In the last step, I canceled all of the negative signs. 

Example Question #141 : Computation Of The Derivative

Determine the derivative of f(x)=2\tan ^2(x^2)

Possible Answers:

4x\tan(x^2)

8x\tan(x^2)\sec^2(x^2)

8x\sec^2(x^2)

4\tan(x^2)\sec^2(x^2)

4x\sec^2(x^2)

Correct answer:

8x\tan(x^2)\sec^2(x^2)

Explanation:

This is a pure problem on understanding how chain rules work for derivatives.

First thing we need to remember is that the derivative of \tan(x) is \sec^2(x).

When we are taking the derivative of f(x)=2\tan ^2(x^2), we can first pull out the 2 in the front and we treat \tan^2(x^2) as [\tan(x^2)]^2.

This way, the derivative will become 2*2*\tan(x^2)*\frac{\mathrm{d} tan(x^2)}{\mathrm{d} x},

which is 4\tan(x^2)*(2x\sec(x^2)).

Example Question #231 : Derivatives

Find  of the following equation:

 

Possible Answers:

Correct answer:

Explanation:

To find  we must use implicit differentiation, which is an application of the chain rule.

Taking  of both sides of the equation, we get

using the following rules:

Note that for every derivative of a function with y, the additional term  appears; this is because of the chain rule, where , so to speak, for the function it appears in. 

Using algebra to rearrange, we get

 

Example Question #141 : Computation Of The Derivative

Find the derivative:

Possible Answers:

Correct answer:

Explanation:

The derivative of the function is equal to

and was found using the following rules:

Before simplification, the derivative we get is

Note that the square root, the exponential, and the tangent function all utilize chain rule when taking their derivatives. 

Example Question #446 : Ap Calculus Ab

Find the first derivative of the following function:

Possible Answers:

Correct answer:

Explanation:

The derivative of the function is equal to

and was found using the following rules:

Note that the first rule - the chain rule - was used three times for the function: the cosine, contained the exponential which itself was raised to a function. (Note that sometimes the exponential rule is written as , which itself is the chain rule.)

Example Question #51 : Chain Rule And Implicit Differentiation

A reaction is modeled by the following equation:

where  are constants.

What is ?

Possible Answers:

Correct answer:

Explanation:

The derivative of the function is equal to

and was found using the following rules:

The chain rule was used for the function contained in the exponential function (or, as written as a rule, ).

Example Question #141 : Computation Of The Derivative

For the equation, , find .

Possible Answers:

Correct answer:

Explanation:

The equation given is not written and . Instead, it is written with 's and 's on the same side of the equation. This suggests we should try implicit differentiation, which means find the derivative of both sides with respect to .

"With respect to " means that we treat every other variable as a function of . So , and the derivative of  is a chain rule. This will be emphasized later in the explanation.

First we must differentiate both sides with respect to .

We have multiple terms on the left hand side, so we will differentiate each term individually.

For the first term, , we will use the power rule and also use the chain rule, since we must assume that .

 

The blue part is the power rule. The red is from the chain rule. The red part is the derivative of y with respect to x, which is currently unknown. Remember that y is some unknown function of x, whose derivative is also unknown. We can only write for the derivative of y.

Now we find the second term's derivative,

This is a product rule. To help with the product rule, the two pieces are color coded. Remember that the power rule is

Applying this, we get

Simplifying gives us

For the third term, , we will algebraically rewrite it as , so we can apply the product rule instead of the quotient rule. This is just a personal preference, The quotient rule would work as well.

remember that the derivative of  with respect to requires the chain rule, resulting in the .Simplifying gives us

The right hand side of the equation is a constant, so its derivative is zero.

Assembling all the parts back together, we have

Now that we have differentiated the equation, we need to algebraically solve for .

First, we should move all terms with a to one side, which in this case is already done. Then we should move all terms without a to the opposite side of the equation. Doing so, we get

Then we will will factor out the common factor of . This results in

Then, to isolate , we divide both sides by .

Now we need to simplify and get rid of the negative exponents. To do this, we can simply multiply the numerator and denominator by . This will result in

Which is the correct answer.

 

 

 

Example Question #453 : Ap Calculus Ab

Given the function , find its derivative. 

Possible Answers:

Correct answer:

Explanation:

Given the function , we can find its derivative using the chain rule, which states that 

where  and   for . We have  and , which gives us 

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