a) x = 4586

b) x = 4242

a)  × 4 = 28

28 : 4 = 7

Vậy 7 × 4 = 28.

b) × 3 = 12

12 : 3 = 4

Vậy 4 × 3 = 12.

c) 6 ×  = 24

24 : 6 = 4

Vậy 6 × 4 = 24.

\(\frac{2}{7}\)x  \(\left(\frac{707}{202}+\frac{707}{3030}+\frac{707}{4242}+\frac{707}{5656}+\frac{707}{7272}\right)\)

\(=\frac{2}{7}\)x   \(\left(\frac{7}{2}+\frac{7}{30}+\frac{1}{6}+\frac{1}{8}+\frac{7}{72}\right)\)

\(=\frac{2}{7}\)x    \(\left(\frac{1260}{360}+\frac{84}{360}+\frac{60}{360}+\frac{45}{360}+\frac{35}{360}\right)\)

\(=\frac{2}{7}\)x   \(\frac{371}{90}=\frac{53}{45}\)

a) x = 74    

b) x = 5 

c) x = 3      

d) x = 14

a,3535/3737-x=2121/7474

35/37-x=21/74

x=35/37-21/74

x=49/74

b,x/1968-217/984=187/492

x/1968=187/492+217/984

x/1968=197/328

x=197.1967/328

x=????

\(\frac{3535}{3737}-x=\frac{2121}{7474}\)

                 \(x=\frac{3535}{3737}-\frac{2121}{7474}\)

                 \(x=\frac{7070}{7474}-\frac{2121}{7474}\)

a)3535/3737-x=2121/7474

x=3535/3737-2121/7474

x=49/74

b)x:1968-217/984=187/492

x:1968=187/492+217/984

x:1968=197/328

x=197/328x1968

x=1182

tick nha bạn

Đáp án cần chọn là: B

\(\left(\frac{505}{707}+\frac{222}{333}\right)\cdot x=\frac{404}{909}\)

 =>     \(\left(\frac{5}{7}+\frac{2}{3}\right)\cdot x=\frac{4}{9}\)

=>                     \(\frac{29}{21}\cdot x=\frac{4}{9}\)

=>                               \(x=\frac{4}{9}:\frac{29}{21}\)

=>                              \(x=\frac{28}{87}\)

TK mk nha!

( 505/707+ 222/333) . x = 404/ 909

29/21 . x = 4/9

x= 4/9 : 29/21

x= 4/9 . 21/29

x= 28/87

Vậy x= 28/87

28/87