Bài2:
a,x-5/3=1/6
x=1/6+5/3
x=1/6+10/6
x=11/6
b,4x+3/4=3 và 1/4
4x+3/4=13/4
4x=13/4-3/4
4x=4
x=4÷4
x=1
c,0,5x-3/2=7/12
1/2x-3/2=7/12
1/2x=7/12+3/2
1/2x=7/12+18/12
1/2x=25/12
x=25/12÷1/2
x=25/12×2/1
x=25/6
d,-4/7=x/21
-4/7=-12/21=x/21
=>x/21=(-12)/21
=>x=-12
Bài 1:
a,2/3+4/3=6/3=2
b,5/4-1/2+-7/8=10/8-4/8+-7/8=10-4+(-7)/8=-1/8
c,(-5/24+0,75+7/12)÷(-2 và 1/8)
=(-5/24+3/4+7/12)÷(-17/8)
=-5/24+18/24+14/24)÷(-17/8)
=-5+18+14/24÷(-17/8)
=27/24÷(-17/8)
=9/8×8/-17
=9/-17
Bài2:tính nhanh
a,-5/7×2/11+-5/7×9/11+1 và 5/7
=-5/7×(2/11+9/11)+12/7
=-5/7×1+12/7
=-5/7+12/7
=7/7=1
b,3/7+(-1/5+-3/7)
=3/7+-1/5+-3/7
=(3/7+-3/7)+-1/5
=0+-1/5
-1/5
