AP Calculus AB : Numerical approximations to definite integrals

Study concepts, example questions & explanations for AP Calculus AB

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Example Questions

Example Question #11 : Numerical Approximations To Definite Integrals

Differentiate

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3csc^{2}x-5cosx

3sec^{2}x-5cosx

Correct answer:

Explanation:

The answer is 

We simply differentiate by parts, remembering our trig rules.

Example Question #14 : Integrals

If   then find .

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The answer is 10.

Example Question #11 : Calculus 3

What is the first derivative of the function \large h(x)=x^{\frac{1}{x}}?

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Correct answer:

Explanation:

First, let .

y=x^{\frac{1}{x}}

We will take the natural logarithm of both sides in order to simplify the exponential expression on the right.

\ln y=\ln x^{\frac{1}{x}}

Next, apply the property of logarithms which states that, in general, \log x^a=a\log x, where  is a constant.

\ln y = \frac{1}{x}\ln x

We can differentiate both sides with respect to .

\frac{d}{dx}\[ln y]=\frac{d}{dx}[\frac{1}{x}\ln x]

We will need to apply the Chain Rule on the left side and the Product Rule on the right side.

\frac{d}{dy}[\ln y]\cdot \frac{dy}{dx}=\frac{1}{x}\cdot \frac{d}{dx}[\ln x]+\ln x\cdot \frac{d}{dx}[\frac{1}{x}]

\frac{1}{y}\cdot \frac{dy}{dx}=\frac{1}{x}\cdot \frac{1}{x} + \ln x\cdot \frac{-1}{x^{2}}

Because we are looking for the derivative, we must solve for .

\frac{dy}{dx}=y\cdot \frac{1}{x^{2}}(1-\ln x)

However, we want our answer to be in terms of  only. We now substitute x^{\frac{1}{x}} in place of .

\frac{dy}{dx}=\frac{x^{\frac{1}{x}}}{x^{2}}(1-\ln x)

Since we let , we can replace  with .

The answer is h'(x)=\frac{x^{\frac{1}{x}}}{x^{2}}(1-\ln x).

Example Question #12 : Numerical Approximations To Definite Integrals

Consider the curve given by the parametric equations below:

What is the equation of the line normal to the curve when ?

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Correct answer:

Explanation:

In order to find the equation of the normal line, we will need the slope of the line and a point through which it passes. If we substitute  into our parametric equations, we can easily obtain the point on the curve.

The normal line is perpendicular to the tangent line. Thus, we should first find the slope of the tangent line.

To find the value of the tangent slope when , we will use the following formula:

Because the normal line is perpendicular to the tangent line, the slope of the normal line is the negative reciprocal of the slope of the tangent line. Thus,

slope of normal = .

We now have the point and slope of the normal line, so we can use point-slope form.

The answer is .

 

Example Question #881 : Ap Calculus Ab

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Example Question #2 : Riemann Sums (Left, Right, And Midpoint Evaluation Points)

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Example Question #3 : Riemann Sums (Left, Right, And Midpoint Evaluation Points)

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Example Question #1 : Riemann Sums (Left, Right, And Midpoint Evaluation Points)

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Example Question #5 : Riemann Sums (Left, Right, And Midpoint Evaluation Points)

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Example Question #1 : Riemann Sums (Left, Right, And Midpoint Evaluation Points)

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