AP Calculus AB : Derivatives

Study concepts, example questions & explanations for AP Calculus AB

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Example Questions

Example Question #165 : Ap Calculus Ab

Find the equation of the line passing through (3,1) and parallel to the tangent line to the following function at x=2:

Possible Answers:

None of the other answers

Correct answer:

Explanation:

To determine the equation of the line, we must first find its slope, which is parallel to that of the tangent line to the function. The tangent line to the function at any point is given by the first derivative of the function:

The following rule was used to find the derivative:

Evaluating the derivative at the given point, we find that the slope of the tangent line to the function is

We now can write the equation of the line using point-slope form:

 

 

Example Question #61 : Derivative At A Point

Find the equation of the line that passes through (2,0) and is perpendicular to the tangent line to the following function at x=0:

Possible Answers:

Correct answer:

Explanation:

To determine the equation of the line, we must first find its slope, which is perpendicular to that of the tangent line to the function. The tangent line to the function at any point is given by the first derivative of the function:

which was found using the following rules:

Evaluating the derivative at the given point, we find that the slope of the tangent line to the function is

However, the line we want has a slope perpendicular to this, so we take the negative reciprocal:

We now can write the equation of the line using point-slope form:

Example Question #163 : Ap Calculus Ab

Find the slope of the line tangent to the curve of f(x) when . Round to the nearest whole number.

Possible Answers:

Cannot be determined from the information provided.

Correct answer:

Explanation:

Find the slope of the line tangent to the curve of f(x) when 

To find the slope of a tangent line, we need to find our first derivative.

To find our derivative, we need to recall two rules.

And

Using these two rules, we can find the derivative of f(x).

Our first term can be derived using our first rule. The derivative of e to the x is just e to the x.

This means that our first term will remain 16e to x.

For our other three terms, we follow the second rule. We will decrease each term's exponent by 1, and then multiply the coefficient by the old exponent.

Notice that the 13 will drop out. It is a constant term, and as such when we multiply it by it's original exponent (0) it wil be reduced to zero as well.

Clean up the above to get:

Now, we are almost there. We need to find the slope when x=-2. To do so, plug in -2 for x and solve.

So, our answer is -2350

Example Question #62 : Derivative At A Point

Find the equation of the line passing through the origin and perpendicular to the tangent to the following function at :

Possible Answers:

Correct answer:

Explanation:

To determine the equation of the line, we must first find its slope, which is perpendicular to that of the tangent line to the function. The tangent line to the function at any point is given by the first derivative of the function:

The first derivative was found using the following rules:

Evaluating the derivative at the given point, we get

Because the slope of the line we want is perpendicular to this line, its slope is the negative reciprocal, or

We can now find the equation of the line using point-slope form:

Example Question #63 : Derivative At A Point

Find the slope, , of  at ?

 

Possible Answers:

Correct answer:

Explanation:

The slope of any point on this function can be determined by plugging the point's x-value into the , the first derivative of .

 

Example Question #64 : Derivative At A Point

Find m in  from the equation, given the point (2,0)

Possible Answers:

Correct answer:

Explanation:

To find the tangent line at the given point, we need to first take the derivative of the given function. 

To find the derivative we need to use product rule. Product rule states that we take the derivative of the first function and multiply it by the derivative of the second function and then add that with the derivative of the second function multiplied by the given first function. To find the derivative of each separate function we need to use power rule. 

Power rule says that we take the exponent of the “x” value and bring it to the front. Then we subtract one from the exponent

Use power rule and we get : 

From here, to find the slope at the given point we plug in "2" for x.

This comes out to equal 

 

 

Example Question #1 : Derivative As A Function

A gun sends a bullet straight up with a launch velocity of 220 ft/s. It reaches a height of s=220t-16t^2 after  seconds. What's the acceleration in of the block after it has been ejected?

Possible Answers:

Correct answer:

Explanation:

Since a=\frac{ds^2}{dt^2}, by differentiating the position function twice, we see that acceleration is constant and . Acceleration, in this case, is gravity, which makes sense that it should be a constant value!

Example Question #2 : Derivatives

The speed of a car traveling on the highway is given by the following function of time:

Consider a second function:

What can we conclude about this second function?

Possible Answers:

It represents the change in distance over a given time .

It represents another way to write the car's speed.

It represents the total distance the car has traveled at time .

 

It has no relation to the previous function.

It represents the rate at which the speed of the car is changing.

Correct answer:

It represents the rate at which the speed of the car is changing.

Explanation:

Notice that the function  is simply the derivative of  with respect to time. To see this, simply use the power rule on each of the two terms. 

Therefore,  is the rate at which the car's speed changes, a quantity called acceleration.

Example Question #1 : Corresponding Characteristics Of Graphs Of ƒ And ƒ'

Find the critical numbers of the function, 

 

 

 

 

 

Possible Answers:

Correct answer:

Explanation:

1) Recall the definition of a critical point: 

The critical points of a function  are defined as points , such that  is in the domain of , and at which the derivative  is either zero or does not exist. The number  is called a critical number of .  

 

2) Differentiate 

 

3) Set to zero and solve for 

The critical numbers are, 

We can also observe that the derivative does not exist at , since the term would be come infinite. However,  is not a critical number because the original function  is not defined at . The original function is infinite at , and therefore  is a vertical asymptote of  as can be seen in its' graph, 

 

  Problem 7 plot

 

 

Further Discussion

In this problem we were asked to obtain the critical numbers. If were were asked to find the critical points, we would simply evaluate the function at the critical numbers to find the corresponding function values and then write them as a set of ordered pairs, 

 

Example Question #2 : Corresponding Characteristics Of Graphs Of ƒ And ƒ'

The function  is a continuous, twice-differentiable functuon defined for all real numbers. 

If the following are true: 

Which function could be ?

Possible Answers:

Correct answer:

Explanation:

To answer this problem we must first interpret our given conditions: 

  •  Implies the function is strictly increasing.
  •  Implies the function is strictly concave down.

We note the only function given which fufills both of these conditions is .

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