- #1
superdave
- 150
- 3
Homework Statement
Start with the power series representation 1/(1-x) = sum from n=0 to inf. of x^n for abs(x) < 1 to find a power series representation for f(x) and determine the radius of convergence.
f(x)=ln(5+x^2)
Homework Equations
The Attempt at a Solution
Okay, so I get
1/(1-q)= sum q^n
Now, the problem lies in the fact that x is to a power of 2.
so if q= (-(x^2)-4) I get 1 / (1-(-(x^2)-4)) but if I want to integrate that, now that x is squared, I don't get the ln.
Can I do it the other way?
integrate first to get:
ln (1-q) = sum q^(n+1) / (n+1) and then replace q? I feel like that shouldn't work.