Bài 1: Tính
a) 5/12 + 3/8 - 1/2 b) 5/9 + 1/6 + 7/12 c) 11/12 - 1/2 - 1/4
= ( 5/12 + 3/8 ) - 1/2 = ( 5/9 + 1/6 ) + 7/12 = ( 11/12 - 1/2 ) - 1/4
= 19/24 - 1/2 = 13/18 + 7/12 = 5/12 - 1/4
= 1/2 = 47/36 = 1/6
Bài 2: Tính
a) 1/2 x 1/3 x 3/4 b) 1/2 : 2/3 x 1/6 c) 1/2 : 1/3 : 1/4
= ( 1/2 x 1/3 ) x 3/4 = ( 1/2 : 2/3 ) x 1/6 = ( 1/2 : 1/3 ) : 1/4
= 1/6 x 3/4 = 3/4 x 1/6 = 3/2 : 1/4
= 1/8 = 9/2 = 6/1
Bài 3 : Tính
a) 5/12 + 3/8 : 1/2 b) 5/8 - 1/6 : 5/6 c) 9/10 : 3 x 1/3
= 5/12 + ( 3/8 : 1/2 ) = 5/8 - ( 1/6 : 5/6 ) = ( 9/10 : 3 ) x 1/3
= 5/12 + 3/4 = 5/8 - 1/5 = 30 x 1/3
= 7/6 = 17/40 = 90