/sci/ - Science & Math

Hi I'm studying group theory and I came across this question.
Define [math]G_1=\{1,2,3,4\}[/math] and define [math]*[/math] so that [math]a*b=a\times b \pmod 5[/math], for all [math]a,b\in G_1[/math]. What is [math]2^{-1}[/math]?
I'm not sure how I'm supposed to approach this question tho. The hint given to me was for [math]x^n[/math] where [math]n<0[/math], [math]x^{-1}*x^{n+1}[/math]

Is there a graphical representation of radius of convergence of power series? I don't get what is means tbqh. The wiki definition of it is: radius of the largest disk in which the series converges. Which means nothing to me

Wow, it's like we should have a thread designed for people to post their stupid questions. Hmmm

>>8718979
>they are being sold the idea by people like /sci/ that diversity is good through the media.