Question

bài 1

1/2 + 3/8

1/2 x 2/9 + 7/9 x 1/2

3/10 + x= 1/2

1/2 + x= 5/6

7/20 - ( 5/8 - 2/5)

 

 

Answer 1

`1/2 + 3/8= 4/8 +3/8= 7/8`

`1/2 xx 2/9 + 7/9 xx 1/2= 1/2 xx ( 2/9 + 7/9)= 1/2 xx 9/9= 1/2 xx 1= 1/2`

`3/10 + x= 1/2=> x= 1/2 - 3/10=>x= x=5/10 - 3/10=>x= 2/10=1/5`

`1/2 + x= 5/6=> x= 5/6 - 1/2= 5/6- 3/6=>x= 2/6=1/3`

`7/20 - ( 5/8 - 2/5)= 7/20 - ( 25/40- 16/40)= 7/20- 9/40= 14/40- 9/40= 5/40=1/8`

`#` \(vy\)

Answer 2

\(a,=\dfrac{1.4}{2.4}+\dfrac{3}{8}\\ =\dfrac{4+3}{8}=\dfrac{7}{8}\\ b,=\dfrac{1}{2}\left(\dfrac{2}{9}+\dfrac{7}{9}\right)\\ =\dfrac{1}{2}.1=\dfrac{1}{2}\\ c,x=\dfrac{1}{2}-\dfrac{3}{10}\\ x=\dfrac{5-3}{10}\\ x=\dfrac{2}{10}=\dfrac{1}{5}\\ d,x=\dfrac{5}{6}-\dfrac{1}{2}\\ x=\dfrac{5}{6}-\dfrac{3}{6}\\ x=\dfrac{5-3}{6}\\ x=\dfrac{2}{6}=\dfrac{1}{3}\\ e,=\dfrac{7}{20}-\left(\dfrac{25-16}{40}\right)\\ =\dfrac{7}{20}-\dfrac{9}{40}\\ =\dfrac{14-9}{40}\\ =\dfrac{1}{8}\)