Câu 1

\(a,\dfrac{2}{5}\times x=4\\ x=4:\dfrac{2}{5}=10\\ b,7:x=\dfrac{4}{5}\\ x=\dfrac{4}{5}\times7=\dfrac{28}{5}\) 

Câu 2

\(=\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\times\dfrac{8}{17}=1\times\dfrac{8}{17}=\dfrac{8}{17}\)

Câu 1: Tìm x:

a)  2/5× x = 4

x=4 : 2/5

x=10

 8/7: x =4/5 

x=8/7:4/5

x=10/7

Câu 2: Tính bằng cách thuận tiện nhất

5/9× 8/17 + 4/9 × 8/17

=(5/9+4/9)x8/17

=1x8/17=8/17

\(5/9× 8/17 + 4/9 × 8/17 =>(5/9+4/9)×8/17 =>1 ×8/17=8/17\)

Câu 2:Đáp số là 8/17 nhé

(5/9+4/9)x8/17

=>1x8/17=8/17

Câu 1: Tìm x:

a)  2/5× x =(thiếu đề)

 8/7: x =4/5 

x=8/7:4/5

x=10/7

Câu 2: Tính bằng cách thuận tiện nhất

5/9× 8/17 + 4/9 × 8/17

=(5/9+4/9)x8/17

=1x8/17=8/17

= (5/6 + 7/6) + (4/15 + 11/15)
= 2 + 1

= 3 

=(5/6+7/6)+(4/15+11/15)

=12/6+15/15

=2+1

=3

đúng ko day

\(=\left(\dfrac{5}{6}+\dfrac{7}{6}\right)+\left(\dfrac{4}{15}+\dfrac{11}{15}\right)=\dfrac{12}{6}+1=2+1=3\)

=(5/6+7/6)+(4/15+11/15)

=12/6+15/15

=2+1

=3

= (5/6 + 7/6) + (11/15 + 4/15)

= 12/6 + 15/15

= 2 + 1

= 3

\(=\dfrac{5}{9}\times\dfrac{7}{4}+\dfrac{13}{9}\times\dfrac{7}{4}\\ =\left(\dfrac{5}{9}+\dfrac{13}{9}\right)\times\dfrac{7}{4}\\ =2\times\dfrac{7}{4}\\ =\dfrac{7}{2}\)

`5/9 : 4/7 + 13/9 xx 7/4`

`= 5/9 xx 7/4 + 13/9 xx 7/4`

`= ( 5/9 + 13/9 ) xx 7/4`

`= 18/9 xx 7/4`

`= 2 xx 7/4`

`=7/2` 

\(=\dfrac{5}{9}\times\dfrac{7}{4}+\dfrac{13}{9}\times\dfrac{7}{4}=\dfrac{7}{4}\times\left(\dfrac{5}{9}+\dfrac{13}{9}\right)=\dfrac{7}{4}\times2=\dfrac{14}{4}=\dfrac{7}{2}\)

\(=\dfrac{5}{9}\times\dfrac{7}{4}+\dfrac{13}{9}\times\dfrac{7}{4}=\dfrac{7}{4}\times\left(\dfrac{5}{9}+\dfrac{13}{9}\right)=\dfrac{7}{4}\times2=\dfrac{7}{2}\)

=\(\dfrac{5}{9}\)x\(\dfrac{7}{4}+\dfrac{13}{9}\)x\(\dfrac{7}{4}\)
=\(\dfrac{7}{4}\)x\(\left(\dfrac{5}{9}+\dfrac{13}{9}\right)\)
=\(\dfrac{7}{4}\)x\(2\)
=\(\dfrac{7}{2}\)

5/9 : 4/7 +13/9 *7/4

=(5/9+13/9)* (4/7:7/4)
=2/1+1/1

=3/1

=3

sửa hộ cái lớp cái !

`4/6+7/13+17/9+19/13+1/9+14/6`

`=(4/6+14/6)+(7/13+19/13)+(17/9+1/9)`

`=18/6+26/13+18/9`

`=3+2+2`

`=7`

\(a.14,52\div1,5-9,81\div1,5\)

\(=\left(14,52-9,81\right)\div1,5\)

\(=4,71\div1,5=3,14\)

\(b.\frac{5}{9}:\frac{4}{7}+\frac{13}{9}\times\frac{7}{4}\)

\(=\frac{5}{9}\times\frac{7}{4}+\frac{13}{9}\times\frac{7}{4}\)

\(=\left(\frac{5}{9}+\frac{13}{9}\right)\times\frac{7}{4}\)

\(=\frac{18}{9}\times\frac{7}{4}\)

\(=2\times\frac{7}{4}\)

\(=\frac{7}{2}\)

14,52:1,5-9,81:1,5=( 14,52-9,81 ) : 1,5

=4,71:1,5

=3,14

con thứ 2 thì mình chịu, bạn tự làm nha.

học tốt lên nhé.  mình chỉ biết làm luôn thôi nhé.

a ) = ( 14,52 - 9,81 ) : 1,5

= 4,71 : 1,5 

= 3,14

b) = 5/9 * 7/4 + 13/9 * 7/4

    = ( 5/9+ 13/9 ) * 7/4

    =         2         * 7/4

    =          3,5 = 7/2