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Practice of Evaluating Taylor Series

This original textbook reading covers part of the AP topic. Follow the AP course outline for complete topic instruction and practice.

This reading includes verified answer corrections and explicitly stated clarifications.

Section 3

Practice of Evaluating Taylor Series

You may come across an integral that you cannot anti-differentiate through the usual integration techniques.

One such integral may be

Original source equation or figure

Thankfully, a Taylor-Series Identity may be used to help solve the integral. As long as the limits of integration are within the interval of convergence of the series, then the value of the integral can be expressed as a Taylor Summation.

Note: The value received from the Taylor Summation will be correct only to a certain extent. Increasing the number of terms in the Taylor Summation will make the value more precise.

The technique can be seen in the works of the next example.

Example 7.3.1

Use the Taylor Series for ex to solve the integral

Original source equation or figure

Since the definite integral is in the interval of convergence, all we have to do is plug -x2 into the Taylor Series for ex and then integrate it term by term.

ex ≈ Original source equation or figure

Plugging in -x2 for x,

Original source equation or figure

Original source equation or figure

The next step is to integrate it term-by-term.

Original source equation or figure

Original source equation or figure

Plugging in the lower and upper bounds...

= Original source equation or figure

= Original source equation or figure

Evaluating the seven term summation, we get the value

.7467

which is correct up to the thousandths-place of the actual value, which is

.7468

Example 7.3.2

Using the Taylor Series for cos x, evaluate the integral

Original source equation or figure

The limits of integration are within the interval of convergence, so we can use the expansion for cos x, replacing x with x4.

Original source equation or figure

= Original source equation or figure

= Original source equation or figure

= Original source equation or figure

= 5.949

The expansion of the above function is

Original source equation or figure

Integrating the expansion...

Original source equation or figure

= Original source equation or figure

Since the integral of Original source equation or figure is ln |1+x|, we have that

ln (1+x) ≈ Original source equation or figure

on the interval -1<x<1.

Review 1.3

Question 1 of 3 · 0 correct

Original source equation or figure; no text transcription supplied.

Select one answer.
The anti-derivative of a function’s Taylor Expansion can help to find a polynomial approximation of the function’s anti-derivative. In the next example, we will show how the Mercator Series is evaluated through the integral of the alternating Geometric Series.

Example 7.3.3

Find the anti-derivative of the Taylor Expansion of

Original source equation or figure

Chapter 7 Problems

For questions 1-3, determine the value of the expansion

  1. Original source equation or figure
  2. Original source equation or figure
  3. Original source equation or figure

For questions 4 and 5, evaluate the infinite sum

  1. Original source equation or figure
  2. Original source equation or figure

The average liger weighs 6.2lbs at birth. One standard deviation is approximately 1.2lbs.

  1. What is the probability of a liger weighing between 5 and 6.2 lbs?
  2. What is the probability of a liger weighing between 6.8 and 7.4 lbs?
  3. What is the probability of a liger weighing between 3.8 and 8.6 lbs?

For the next five questions, evaluate the definite integrals using a five-term Taylor Expansion

  1. Original source equation or figure
  2. Original source equation or figure
  3. Original source equation or figure
  4. Original source equation or figure
  5. Original source equation or figure
  1. Original source equation or figure

= Original source equation or figure

The expansion follows the series..

Original source equation or figure,

where x= Original source equation or figure. Therefore,

Original source equation or figure

  1. Original source equation or figure

The expansion follows the series...

ex ≈ Original source equation or figure

where x=420. Therefore, the expansion is equal to

e420

  1. Original source equation or figure

= Original source equation or figure

The expansion follows the series...

Original source equation or figure,

where Original source equation or figure. Therefore,

Original source equation or figure

  1. Original source equation or figure

The summation follows the series..

Original source equation or figure

Where x=1. Therefore,

sin-1(1) = Original source equation or figure .

  1. Original source equation or figure

The summation follows the alternating harmonic series. Expanding the summation...

Original source equation or figure

The expansion follows the series...

Original source equation or figure

where x=1. Therefore,

ln(2)=.693

  1. A weight between 5 and 6.2 pounds falls one standard deviation from the norm.

The values for a and b are

a= -1, b=0. Plugging it into the formula..

Original source equation or figure

Original source equation or figure. Using the exponential taylor series..

Original source equation or figure

Original source equation or figureOriginal source equation or figure

Original source equation or figure

=34.1%

  1. A weight between 6.8 and 7.4 pounds falls between half and one standard deviation from the norm.

The values for a and b are

a= .5, b=1. Plugging it into the formula..

Original source equation or figure

Original source equation or figure. Using the exponential taylor series..

Original source equation or figure

Original source equation or figureOriginal source equation or figure

Original source equation or figure

=14.99%

  1. A weight between 3.8 and 8.6 pounds falls between two standard deviations to the left and right of the norm.

The values for a and b are

a= -2, b=2. Plugging it into the formula..

Original source equation or figure

Original source equation or figure. Using the exponential taylor series..

Original source equation or figure

Original source equation or figureOriginal source equation or figure

12π[z−z36+z540−z7336+z93456]−22=23329452π(1/√(2π))[z−z^3/6+z^5/40−z^7/336+z^9/3456]_{−2}^{2}=2332/(945√(2π))

The first five terms give 0.984479786, or about 98.44798%. This truncation is too coarse for the full probability. Using sixteen terms (n = 0 through 15) gives 0.954499736, or about 95.45%, with next-term error at most 1.515 × 10⁻¹⁰.



  1. Original source equation or figure

Using a five-term expansion..

Original source equation or figure

Original source equation or figure

Original source equation or figure Original source equation or figure

=Original source equation or figure

= .998

  1. Original source equation or figure

Using a five-term expansion..

Original source equation or figure

x21−x43!+x65!−x87!+x109!x^2−x^4/3!+x^6/5!−x^8/7!+x^10/9!

x33−x55⋅3!+x77⋅5!−x99⋅7!+x1111⋅9!x^3/3−x^5/(5⋅3!)+x^7/(7⋅5!)−x^9/(9⋅7!)+x^11/(11⋅9!)Original source equation or figure

= 133−155⋅3!+177⋅5!−199⋅7!+11111⋅9!1/3−1/(5⋅3!)+1/(7⋅5!)−1/(9⋅7!)+1/(11⋅9!)

= .301168

  1. Original source equation or figure

Using a five-term expansion..

Original source equation or figure

Original source equation or figureOriginal source equation or figure

Original source equation or figure`= 1.656

  1. Original source equation or figure

Using a five-term expansion..

Original source equation or figure

Original source equation or figure

x3/3-x4/8+x5/15-x6/24+x7/35x^3/3-x^4/8+x^5/15-x^6/24+x^7/35Original source equation or figure

= (1/2)3/3-(1/2)4/8+(1/2)5/15-(1/2)6/24+(1/2)7/35(1/2)^3/3-(1/2)^4/8+(1/2)^5/15-(1/2)^6/24+(1/2)^7/35

= .0355

  1. Original source equation or figure

Using a five-term expansion..

Original source equation or figure

Original source equation or figure

= Original source equation or figureOriginal source equation or figure

= Original source equation or figure

= .2496

Glossary and deeper reading · 1 refreshers

These editorial refreshers supplement the reading. Definitions and examples are added guidance; original source wording and recorded answers remain in their original context.

  • Taylor series

    A Taylor series is the infinite power series built from a function’s derivatives at a chosen center. Its coefficients are the derivatives at the center divided by the corresponding factorials. For example, eˣ has Taylor series 1+x+x²/2!+x³/3!+⋯ centered at 0. A Taylor series represents the function only where convergence and the vanishing remainder justify that equality.

    Read more: 10.14 · Taylor series →

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