HW #06
Due: 10/27/2025
1.
password2.jpg
What is the 10 digit WiFi password? Penalty if you actually compute the integral.


2.
By expanding x4 by the Fourier series, obtain



n=1 
1

n4
.
Hint: You can use the result of


n=1 
1

n2
from #14 lecture
Integrate with respect to
from to .

Examples: Cos[x], Sin[m x], Exp[x], Pi, Infinity, Tan[x] etc..



3.
Solve the following differential equation using the Fourier series and plot the first three non-zero terms over −π < x < π.

u"(x) = f(x),     u(−π)=0,     u(π) = 0,
where
f(x) =



−1
    −π < x < 0
1
    0 < x < π.



File translated from TEX by TTH, version 4.03.
On 19 Oct 2025, 21:05.