Example 2. Consider
the function
.
2 (a). Find the terms
up to
in
the Maclaurin series for f[x].
Solution 2 (a).
2 (a). Find the
terms up to
in
the Maclaurin series for f[x].
Remark. If you just
find the "Series" it will include a "Big
" term,
which cannot be used in either evaluations or graphing, we eliminate
it with the command "Normal." The "Big
term
lets us know the power of x in the "remainder.
Aside. Of course
the "full" Maclaurin series has an infinite number of
terms. Mathematica is capable of finding sums of
infinite series.
The following is just for fun !
There are two ways to get infinite sums, the old way and the new
way.
The "symbolic" command is:
Now graph f[x] and the Maclaurin polynomial s[x] over the interval [-2, 2].
![[Graphics:../Images/TaylorPolyMod_gr_127.gif]](../Images/TaylorPolyMod_gr_127.gif)
The curves are distinct, but this is only evident if we look at them over a larger interval.
![[Graphics:../Images/TaylorPolyMod_gr_130.gif]](../Images/TaylorPolyMod_gr_130.gif)
Background for part 2 (b). Use the fact that the series is "alternating" to investigate the error for the Maclaurin polynomial of degree n = 10 over the interval [-2.0, 2.0].
Now look closely at the "error" when the series is used to approximate the function. How close are were the two curves in part (a) ?
![[Graphics:../Images/TaylorPolyMod_gr_133.gif]](../Images/TaylorPolyMod_gr_133.gif)
This series is "very nice" because it is alternating, and for that reason the error bound is the magnitude of the "next non-zero term" in the series.
The error bound for the entire interval [-2.0, 2.0] is
This estimate is "conservative" and is a little larger than the
"actual" maximum error which occurred at
(c) John H. Mathews 2004