Cho t?p h?p A g?m n ph?n t? (n ? 1). M?i k?t qu? c?a s? s?p x?p th? t? n ph?n t? c?a t?p h?p A ???c g?i là m?t hoán v? c?a n ph?n t? ?ó./Toán H?c /Hoán V? – Ch?nh h?p – T? H?p: Công Th?c & Các D?ng Ví D? C? B?nYour browser won't support the audio aspect. Your browser does not assistance the audio component. Your browser doesn't help the