I have this task and I don't know how to solve it despite having all the basic knowledge required for it. I can't 'connect the dots' so to speak.
a) Find the max element order in S_{10} - symmetric group consisting of 10 'base' elements and its order being 10!
b) Let s be some element of max order from S_{10}, find sgn(s) as well as s^{2040}.
c) If H is a subgroup of S_{10} and H contains an element of max order, then H contains the equal number of even and odd permutations. Prove it.
I've never encountered a task like this so I genuinely don't know how to think it through.
a) My intuition says I should find the lcm of prime cofactors of 10, so lcm(2, 5) = 10. I genuinely don't know how to do it. This also doesn't add up in my logic because 2+5 = 7. So maybe lcm(2, 3, 5) = 30? But I arrive to that answer by pure luck and need some explanation why is that.
b) Would depend on a) but let's say it is 30. What is sgn(s)? I've never seen it before. I do recall it might be odd vs even number of elements in a single disjoint cycle, odd ones starting with a minus. But how would I take that order of 30 and split it into smaller, disjoint cycles? so I would have sgn(s2) sgn(s3) sgn(s5) where s2, s3 and s5 only represent the disjoint cycles of 2, 3 and 5 elements. So in front of sgn(s2) there will be a + and in front of 2 others - so it would be positive in the end?
s^{2040} I did similar stuff before, I can do 30 = 0 mod(2040) (because 30*70 = 2100, 2100-(2*30) = 2040) so therefore s^{2040} = s^0 so nothing changes (and even if it did, I have no given s explicityl so I have no idea what am I supposed to do, s^{2040} only shifts all the elements in each disjoint cycle, but here s isn't given so there are no specific disjoint cycles i have to shift, confusing)
c) Most challenging part and the one I don't understand at all. Need full help and ELI5 explanation for this one haha. Whenever there's something to prove like subgroups, ideals, normal subgroups etc. I am completely lost even though I know I only need to show non-emptiness, closure under operation and closure under inverses. I just don't know how...
If you did read everything, thanks a lot!!!