\(x+\frac{4}{5}=\frac{45}{5}-\left(\frac{3}{7}+\frac{3}{5}\right)\)

\(x+\frac{4}{5}=9-\frac{36}{35}\)

\(x+\frac{4}{5}=\frac{279}{35}\)

\(\Rightarrow x=\frac{251}{35}\)

\(x+\frac{4}{5}=\frac{45}{5}-\left(\frac{3}{7}+\frac{3}{5}\right)\)

\(\Leftrightarrow x+\frac{4}{5}=9-\left(\frac{3}{7}+\frac{3}{5}\right)\)

\(\Leftrightarrow x+\frac{4}{5}=9-\frac{3}{7}-\frac{3}{5}\)

\(\Leftrightarrow x+\frac{4}{5}=\frac{315}{35}-\frac{15}{35}-\frac{21}{35}\)

\(\Leftrightarrow x+\frac{4}{5}=\frac{279}{35}\)

\(\Leftrightarrow x=\frac{279}{35}-\frac{4}{5}\)

\(\Leftrightarrow x=\frac{251}{35}\)

\(\frac{5}{7}+\frac{x}{35}=\frac{4}{5}\)

\(\Leftrightarrow\frac{25}{35}+\frac{x}{35}=\frac{28}{35}\)

\(\Leftrightarrow25+x=28\)

\(\Leftrightarrow x=28-25\)

\(\Leftrightarrow x=3\)

a) \(6-\dfrac{2}{5}+\dfrac{3}{5}\) x \(3\)

\(=6-\dfrac{2}{5}+\dfrac{9}{5}\)

\(=\dfrac{30}{5}-\dfrac{2}{5}+\dfrac{9}{5}\)

\(=\dfrac{30-2+9}{5}=\dfrac{37}{5}\)

b) \(\left(\dfrac{31}{35}-\dfrac{4}{7}\right)\) x \(\dfrac{8}{7}:2\)

\(=\left(\dfrac{31}{35}-\dfrac{20}{35}\right)\) x \(\dfrac{8}{7}:2\)

\(=\dfrac{11}{35}\) x \(\dfrac{8}{7}:2\)

\(=\dfrac{11}{35}\) x \(\dfrac{8}{7}\) x \(\dfrac{1}{2}\)

\(=\dfrac{\text{11 x 8 x 1}}{\text{ 35 x 7 x 2}}=\dfrac{88}{490}=\dfrac{88}{245}\)  

a) 6−25+356−25+35 x 33

=6−25+95=6−25+95

=305−25+95=305−25+95

=30−2+95=375=30−2+95=375

b) (3135−47)(3135−47) x 87:287:2

=(3135−2035)=(3135−2035) x 87:287:2

=1135=1135 x 8

Học sinh nhẩm và ghi kết quả như sau:

7 x 5 = 35

7 x 6 = 42

7 x 2 = 14

7 x 4 = 28

35 : 7 =5

42 : 7 = 6

14 : 7 = 2

28: 7 =4

35 : 5 = 7

42 : 6 = 7

14 : 2 = 7

28 : 4 = 7

a) 14/15

b) 1/20

c) 4/7

d) 49/50

\(a\) \(\dfrac{3}{5}+\dfrac{1}{3}=\dfrac{9}{15}+\dfrac{5}{15}=\dfrac{14}{15}\)

\(b\) \(\dfrac{17}{20}-\dfrac{4}{5}=\dfrac{17}{20}-\dfrac{16}{20}-\dfrac{1}{20}\)

\(c\) \(\dfrac{25}{35}\times\dfrac{4}{5}=\dfrac{5}{7}\times\dfrac{4}{5}=\dfrac{4}{7}\)

\(d\) \(\dfrac{7}{15}:\dfrac{6}{7}=\dfrac{7}{15}\times\dfrac{7}{6}=\dfrac{49}{90}\)

a. 14/15

b. 1/20

c. 4/7

d. 49/90

\(\frac{6-2}{5}+\frac{3}{5.3}\)

\(=\frac{4}{5}+\frac{1}{5.1}\)

\(=\frac{4}{5}+\frac{1}{5}\)

\(=\frac{5}{5}=1\)

a. 6 x 3 - ( \(\frac{2}{5}+\frac{3}{5}\)) = 6 x 3 - \(\frac{5}{5}\)= 6 x 3 - 1 = 18 - 1 = 17

b.(  \(\frac{31}{35}-\frac{4}{7}\)) x \(\frac{8}{7}\): 2 =\(\frac{11}{35}\)x \(\frac{8}{7}\): 2 =\(\frac{88}{245}\): 2 = \(\frac{88}{490}\)= \(\frac{44}{245}\)= ...........rút gọn đến khi hết

a) \(6-\frac{2}{5}+\frac{3}{5}\times3\)

\(=6-\frac{2}{5}+\frac{9}{5}\)

\(=\frac{30}{5}-\frac{2}{5}+\frac{9}{5}\)

\(=\frac{28}{5}+\frac{9}{5}\)

\(=\frac{37}{5}\)

b) \(\left(\frac{31}{35}-\frac{4}{7}\right)\times\frac{8}{7}:2\)

\(=\frac{11}{35}\times\frac{8}{7}:2\)

\(=\frac{88}{245}:2\)

\(=\frac{44}{245}\)

2: 

a: =>x=1/2+1/6=3/6+1/6=4/6=2/3

b: =>x+3,5=7,8-6,3=1,5

=>x=1,5-3,5=-2

c: =>(35-x)/-105=1/5

=>35-x=-21

=>x=56

1

c hình như tính bình thường thôi:v

d

= 1,75 : 5 + 2,5 . (16 – 4 . 4,1)

= 1,75 : 5 + 2,5 . (16 – 16,4)

= 1,75 : 5 + 2,5 . (−0,4)

= 0,35 − 1

= −0,65.

2

a

\(\Rightarrow x=\dfrac{1}{2}+\dfrac{1}{6}=\dfrac{3}{6}+\dfrac{1}{6}=\dfrac{4}{6}=\dfrac{2}{3}\)

b

\(\Rightarrow x+\dfrac{35}{10}=\dfrac{78}{10}-\dfrac{63}{5}:2\\ \Rightarrow x+\dfrac{35}{10}=\dfrac{78}{10}-\dfrac{63}{10}=\dfrac{15}{10}\\ \Rightarrow x=\dfrac{15}{10}-\dfrac{35}{10}=-2\)

c không rõ đề:v

\(1,\dfrac{2}{-11}.6\dfrac{2}{7}+\dfrac{3}{7}:3+5\\ =\dfrac{2}{-11}.\dfrac{44}{7}+\dfrac{3}{7}\times\dfrac{1}{3}+5\\ =-\dfrac{88}{77}+\dfrac{3}{21}+5\\ =-\dfrac{8}{7}+\dfrac{1}{7}+5\\ =-1+5\\ =4\)

\(d,1,75:5+2,5.\left(4^2-4.4,1\right)\\ =0,35+2,5.\left(16-16,4\right)\\ =0,35+2,5.0,4\\ =0,35+1\\ =1,35\)

`2,`

`a, 1/2 -x=-1/6`

`=> x= 1/2 -(-1/6)`

`=> x= 1/2 +1/6`

`=> x= 3/6+1/6`

`=>x= 4/6`

`=>x=2/3`

Vậy `x=2/3`

`b, x+3,5 =7,8 -12,6 :2`

`=> x+3,5 = 7,8 - 6,3`

`=> x+3,5=1,5`

`=> x= 1,5-3,5`

`=>x=-2`

Vậy `x=-2`

\(c,\dfrac{7}{35}=\dfrac{35-x}{-105}\\ \Rightarrow7.\left(-105\right)=35.\left(35-x\right)\\ \Rightarrow-735=1225-35x\\ \Rightarrow-735-1225=-35x\\ \Rightarrow-1960=-35x\\ \Rightarrow x=-1960:\left(-35\right)\\ \Rightarrow x=56\)

Vậy `x=56`

9 x 5 = 45

63 : 7 = 9

8 x 8 = 64

5 x 7 = 35

8 x 7 =56

3 x 8 = 24

40 : 5 = 8

5 x 5 = 25

7 x 5 = 35

7 x 8 =56

6 x 4 = 24

45 : 9 = 5

7 x 7 = 49

35 : 5 = 7

56 : 8 = 7

2 x 8 = 16

81 : 9 = 9

9 x 9 = 81

35 : 7 = 5

56 : 7 = 8

ay bạn ơi dễ vậy mà

`x + 4/5= 45/5 -( 3/7 + 3/5)`

`=> x+ 4/5=9 - 36/35`

`=> x+ 4/5=279/35`

`=> x= 279/35 -4/5`

`=>x= 251/35`

__

`5/7 + x/35 = 4/5`

`=>  x/35 = 4/5-5/7`

`=>  x/35 =28/35 - 25/35`

`=> x/35= 3/35`

`=>x=3`

`@ `\(MinYewCou\)

ok