6 + 1 = 7     5 + 2 = 7     4 + 3 = 7

1 + 6 = 7     2 + 5 = 7     3 + 4 = 7

7 - 6 = 1     7 - 5 = 2     7 - 4 = 3

7 - 1 = 6     7 - 2 = 5     7 - 3 = 4

Lời giải chi tiết:

\(=\dfrac{2}{35}\cdot\dfrac{5}{6}\cdot7+\dfrac{5}{2}\cdot\dfrac{7}{6}\cdot\dfrac{8}{9}\cdot\dfrac{7}{2}=\dfrac{1}{3}+\dfrac{245}{27}=\dfrac{245+9}{27}=\dfrac{254}{27}\)

Nhìn nó rối ghê á

1: =-15+10-35+28=-32

rối thật đó

1: =-15+10-35+28=-12

3: =20-12-8+12=12

2) -3(4 - 7) + 5(-3 + 2)

= -3.4 + 3.7 - 5.3 + 5.2

= -12 + 21 -15 + 10

= 31 - 27

= 4

4) -5(2 - 7) + 4(2 - 5)

= -5.2 + 5.7 + 4.2 - 4.5

= -10 + 35 + 8 - 20

= 38 - 30

= 8

5) 6(-3 - 7) - 7(3 + 5)

= -6.3 - 6.7 - 7.3 - 7.5

= -18 - 42 - 21 - 35

= -116

6) 3(-5 + 6) - 4(3 - 2)

= -3.5 + 3.6 - 4.3 + 4.2

= -15 + 18 - 12 + 8

= 26 - 27

= -1

Lời giải chi tiết:

tat ca deu bang 10

1+5+1+=?

1+3+8=?

2+4+9=?

3: \(=20-12-8+12=20-8=12\)

5: \(=-18-42-21-35=-116\)

3: \(=-15+18-12+8=-27+26=-1\)

2: \(=-12+21-15+10=9-5=4\)

`1/7+5/6+4/7+3/6+2/7+4/6` 

`=(1/7 + 4/7 + 2/7 )+(5/6 + 3/6 +4/6)`

`= 7/7 + 12/6`

`=1+2`

`=3`

`1/7+5/6+4/7+3/6+2/7+4/6`

`=(1/7+4/7+2/7)+(5/6+3/6+4/6)`

`=7/7+12/6`

`=1+2`

`=3`

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

5 + 4 = 9     1 + 6 = 7     4 + 2 = 6     9 + 1 = 10     2 + 7 = 9

9 - 5 = 4     7 - 1 = 6     6 - 4 = 2     10 - 9 = 1     9 - 2 = 7

9 - 4 = 5     7 - 6 = 1     6 - 2 = 4     10 - 1 = 9     9 - 7 = 2

5+4 = 9            1 + 6 = 7

5 + 4 = 9        1 + 6 = 7         4 + 2 = 6        9 + 1 = 10         2 + 7 = 9

9 -  5  = 4       7 - 1 = 6          6 - 4 = 2         10 - 9 = 1          9 - 2 =  7

9 - 4 = 5         7 - 6 = 1          6 - 2 = 4          10 - 1 = 9         9 - 7 = 2