(-12)x7+(-8)x7+4x(-25)+(-6)x(-25)=(-12-8)x7+(-25)(4x-6x)=7x(-20)+(-25)(-2x)=-140x+50x=-90x

Lời giải:

$\frac{6}{4}\times \frac{19}{10}-\frac{3}{4}\times \frac{7}{10}+\frac{3}{4}:\frac{10}{69}$

$=\frac{6}{4}\times \frac{19}{10}-\frac{3}{4}\times \frac{7}{10}+\frac{3}{4}\times \frac{69}{10}$

$=\frac{6}{4}\times \frac{19}{10}+\frac{3}{4}\times (\frac{69}{10}-\frac{7}{10})$

$=\frac{3}{2}\times \frac{19}{10}+\frac{3}{4}\times \frac{62}{10}$

$=\frac{3}{2}\times \frac{19}{10}+\frac{3}{2}\times \frac{31}{10}$
$=\frac{3}{2}\times (\frac{19}{10}+\frac{31}{10})$

$=\frac{3}{2}\times \frac{50}{10}=\frac{3}{2}\times 5=\frac{15}{2}$

ai cũng giống chắc đúng rồi, nhưng giải ra cho mình đi

Ta có \(\frac{2.3.4+2.3.4.2018+2.3.4.2019-2.3.4.2020}{5.6.7+5.6.7.2018+5.6.7.2019-5.6.7.2020}\)

\(=\frac{2.3.4\left(1+2018+2019-2020\right)}{5.6.7.\left(1+2018+2019-2020\right)}=\frac{2.3.4}{5.6.7}=\frac{4}{35}\)

8 x 6 = 48

8 x7 = 56

8 x 8 = 64

8 x 9 = 72

48 : 8 = 6

56 : 8 = 7

64 : 8 = 8

72 : 8 = 9

`@` `\text {Ans}`

`\downarrow`

`a)`

`20 \times 6 \times 5 \times 7`

`= (6 \times 7) \times (20 \times 5)`

`= 42 \times 100`

`= 4200`

`b)`

`125 \times 789 \times 8`

`= (125 \times 8) \times 789`

`= 1000 \times 789`

`= 789000`

`c)`

`2 \times 3 \times 4 \times 8 \times 50 \times 25 \times 125`

`= (2 \times 50) \times 3 \times (4 \times 25) \times (8 \times 125)`

`= 100 \times 3 \times 100 \times 1000`

`= 300000000`

a) 20 x 6 x 5 x 7

= ( 20 x 5 ) x ( 6 x 7 )

= 100 x 42

= 4200

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