Bài 6:
a)5/7=5x9/7x9=45/63
8/9=8x7/9x7=56/63
b)13/24 giữ nguyên
5/6=5x4/6x4=20/24
c)4/7=4 x11x2 / 7x11x2=88/152
6/11=6x7x2 / 11x7x2=84/152
1/2=1x7x11 / 2x7x11=77/152
d)2/3=2x5/3x5=10/15
4/15 giữ nguyên
Bài 7:
a)8/12=2/3
20/48=5/12
1515/1515=1
b)4x2x9/3x2x2=2x2x2x3x3/3x2x2=1x1x2x1x3/1x1x1=6
c)11x9x6x7/9x66x7x44=11x1x6x1/1x11x6x1x11x4=1/44
Bài 8:
1/5 gấp 4 lần 1/20
Bài 9:
b
Bài 11:
20/12+36/18-21/28
=10/6+12/6-3/4
=22/6-3/4
=44/12-9/12
=53/12
2-(2/5+2/3)
=2-(6/15+10/15)
=2-16/15
=2/1-16/15
=30/15-16/15
=14/15
Bài 12:
a)yx1/2=3/4
y =3/4:1/2
y =6/4=3/2
b)y:9/16=8/27
y =8/27x9/16
y =1/6
c)3/4:y=7/9+2/7
3/4:y=67/63
y=3/4:67/63
y=189/268
xin câu trả lời hay nhất
