Bài 1 : Tính bằng hai cách a) (5/4+2/5):5/6 b) 3/4×2/5-3/4*2/7 c) 2/3 : (5/6×9/10) 22/09/2021 Bởi Samantha Bài 1 : Tính bằng hai cách a) (5/4+2/5):5/6 b) 3/4×2/5-3/4*2/7 c) 2/3 : (5/6×9/10)
a) (5/4+2/5):5/6 C1: 33/20 : 5/6 = 99/50 C2: (5/4+2/5):5/6 = 5/4 : 5/6 + 2/5 : 5/6 = 3/2 + 12/25 = 99/50 b) 3/4 x 2/5 – 3/4 x 2/7 C1: 3/10 – 3/14 = 3/35 C2: 3/4 x 2/5 – 3/4 x 2/7 = (2/5 – 2/7) x 3/4 = 4/35 x 3/4 = 3/35 c) 2/3 : (5/6 x 9/10) C1: 2/3 : 3/4 = 8/9 C2: 2/3 : (5/6 x 9/10) = (2/3 x 5/6) : (2/3 x 9/10) = 8/9 Bình luận
a) (5/4+2/5):5/6
C1: 33/20 : 5/6
= 99/50
C2: (5/4+2/5):5/6
= 5/4 : 5/6 + 2/5 : 5/6
= 3/2 + 12/25
= 99/50
b) 3/4 x 2/5 – 3/4 x 2/7
C1: 3/10 – 3/14
= 3/35
C2: 3/4 x 2/5 – 3/4 x 2/7
= (2/5 – 2/7) x 3/4
= 4/35 x 3/4
= 3/35
c) 2/3 : (5/6 x 9/10)
C1: 2/3 : 3/4
= 8/9
C2: 2/3 : (5/6 x 9/10)
= (2/3 x 5/6) : (2/3 x 9/10)
= 8/9