\(\dfrac{1}{4}\times\dfrac{5}{12}+\dfrac{5}{12}\times\dfrac{4}{5}=\dfrac{5}{12}\times\left(\dfrac{1}{4}+\dfrac{4}{5}\right)=\dfrac{5}{12}\times\left(\dfrac{5}{20}+\dfrac{8}{20}\right)=\dfrac{5}{12}\times\dfrac{13}{20}=\dfrac{13}{48}\)

\(C_1:\dfrac{1}{4}\times\dfrac{5}{12}+\dfrac{5}{12}\times\dfrac{4}{5}=\dfrac{5}{48}+\dfrac{1}{3}=\dfrac{7}{16}\)

\(C_2:\dfrac{1}{4}\times\dfrac{5}{12}+\dfrac{5}{12}\times\dfrac{4}{5}=\dfrac{5}{12}\times\left(\dfrac{1}{4}+\dfrac{4}{5}\right)=\dfrac{5}{12}\times\dfrac{21}{20}=\dfrac{7}{16}\)

500 500m2  >  1/2km2 50m2

tích cho mik

`6+7-8xx9:10`

`=6+7-72:10`

`=6+7-7,2`

`=13-7,2`

`=5,8`

= 6+7-72:10

=6+7-7,2

=13-7,2

=5,8 nha

2020/2018 

= 2020:2/2018:2

= 1010/1009

Vậy 2020/2018 rút gọn thành 1010/1009

`4/5-5/10`

`=8/10-5/10`

`=3/10`

=8/10-5/10=3/10

a >

B <

a)Ta có : 404303/303202=1+101101/303202

303202/202101=1+101101/202101

Do 101101/303202<101101/202101 ⇒404303/303202>303202/202101

`1/2:2/3`

`=1/2xx3/2`

`=3/4`

1/2:2/3

=1/2x3/2

=3

`2/3-3/8`

`=16/24-9/24`

`=7/24`

$2/3-3/8$

$=16/24-9/24$

$=7/24$

7/10=1/2+1/5

`1 xx 5/4`

`=(1xx5)/4`

`=5/4`

1 x \(\dfrac{5}{4}\)= \(\dfrac{1}{1}\) x \(\dfrac{5}{4}\) = \(\dfrac{5}{4}\)