Recent content by avdnowhere

i've a lecture note about this question... but the note is different from the question... so i don't know how to start it...

hi guys... this is my first thread in this forum.. i hope i'll learn math more easily with this forum... mmm.. i've a some math homework that i must submit it this Thursday... :-p but, i don't know how to answer it... the questions is... 1. Prove that X ⊆ X U Y for all sets...