- #1
MissP.25_5
- 331
- 0
Hello.
I need someone to explain to me how to find the centre and radius of convergence of power series.
I got the working and the answers but there are some things I don't understand.
$$\sum_{n=0}^{\infty}\frac{(4i)^n(z-i)^n}{(n+1)(n+2)}$$
Using the ratio test, we got
$$\lim_{{n}\to{\infty}} \frac{4i(z-i)(n+1)}{n+3}$$=4i(z-i)
Ok, in this part, why is the limit 4i(z-i)? Don't we have to divide all the terms by n?
And the final answer is: $$R=1/4, z=i$$
Why does the centre become i?
I need someone to explain to me how to find the centre and radius of convergence of power series.
I got the working and the answers but there are some things I don't understand.
$$\sum_{n=0}^{\infty}\frac{(4i)^n(z-i)^n}{(n+1)(n+2)}$$
Using the ratio test, we got
$$\lim_{{n}\to{\infty}} \frac{4i(z-i)(n+1)}{n+3}$$=4i(z-i)
Ok, in this part, why is the limit 4i(z-i)? Don't we have to divide all the terms by n?
And the final answer is: $$R=1/4, z=i$$
Why does the centre become i?