a) Tìm UCLN (56, 84, 140)
56 = 23 . 7
84 = 22 . 3 . 7
140 = 22 . 5 . 7
UCLN (56, 84, 140) = 22 . 7 = 28
➤ UCLN (56, 84, 140) = 28
b) BCNN (72, 90, 108)
72 = 23 . 32
90 = 2 . 32 . 5
108 = 22 . 33
BCNN (72, 90, 108) = 23 . 33 . 5 = 1080
➤ BCNN (72, 90, 108) = 1080
a, 56 = 23 . 7 ; 84 = 22 . 3 . 7 ; 140 = 22 . 5 .7
ƯCLN ( 56, 84, 140) : 22 . 7 = 28
b 72 = 23 . 32; 90 = 2 . 32 . 5 ; 108 = 22 . 33
BCNN ( 72, 90, 108 ) : 23 . 33 . 5 = 1080
