Using known Maclaurin series to approximate modification of original

Click For Summary
SUMMARY

The discussion focuses on using the Maclaurin series to approximate the function f(x) = xsin(x/2). The Maclaurin series for sin(x) is given by the formula ∑((-1)^{k}x^{2k+1})/(2k + 1)!. Participants confirm that substituting x/2 into the series for sin(x) is valid, leading to the expression x∑((-1)^{k}(x/2)^{2k+1})/(2k + 1)!. Additionally, it is noted that simplifying the series by shifting summation bounds can enhance the approximation.

PREREQUISITES
  • Understanding of Maclaurin series and Taylor series expansions
  • Familiarity with factorial notation and its application in series
  • Basic knowledge of trigonometric functions, specifically sin(x)
  • Ability to manipulate summations and series terms
NEXT STEPS
  • Study the derivation and applications of Taylor series in calculus
  • Learn about convergence criteria for power series
  • Explore advanced techniques for series manipulation and simplification
  • Investigate the use of Maclaurin series in solving differential equations
USEFUL FOR

Students studying calculus, particularly those focusing on series expansions, mathematicians interested in approximation techniques, and educators teaching series convergence and manipulation.

phosgene
Messages
145
Reaction score
1

Homework Statement



Recall that the Maclaurin series for sin(x) is \sum\frac{(-1)^{k}x^{2k+1}}{(2k + 1)!}.

Use this formula to find the Maclaurin polynomial P5(x) for f(x)=xsin(x/2).

Homework Equations


The Attempt at a Solution



I know that to approximate sin(x/2) with the Maclaurin polynomial for sinx, I just substitute x/2 for x. But for xsinx, since the Maclaurin series is approximating sinx, can I just substitute the series for sinx so that I get x\sum\frac{(-1)^{k}x^{2k+1}}{(2k + 1)!}?
 
Physics news on Phys.org


yes you can :smile:
 


Yes. You can make that better if you now sweep the x inside the sum. You may also want to include the summation bounds as you can sometimes simplify further by shifting them.
 


Sorry, didn't see that I forgot the bounds. It's supposed to be from n=0 to infinity. Thanks for the help guys :)
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 38 ·
2
Replies
38
Views
3K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 2 ·
Replies
2
Views
5K
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
22K