92 x 87 + 207 x 87 + 87 = 87 x ( 92 + 207 + 1 )

                                          = 87 x 300

                                          = 26100

92 x 87 + 207 x 87 + 87

= 87 x ( 92 + 207 + 1 )

= 97 x 300

= ( 100 - 3 ) x 300

= 100 x 300 - 3 x 300

= 30000 - 900

= 29100

a) 415 x 7 - 415 x 5 + 415 x 8

= 415 x (7 - 5 + 8)

= 415 x 10

= 4150

b) 23 x 87 + 12 x 23 + 23

= 23 x 87 + 12 x 23 + 23 x 1

= 23 x (87 + 12 + 1)

= 23 x 100

= 2300

HHehe

Ta có : \(B=\frac{175.88-87}{88+175.87}=\frac{175.\left(87+1\right)-87}{88+175.87}=\frac{175.87+175-87}{88+175.87}=\frac{175.87+88}{88+175.87}=1\)

P/S : Dấu"." là dấu "x"

Cảm ơn bạn nhiều nhé :3

2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40

= 24 x 53 + 24 x 87 - 24 x  40

= 24 x ( 53 + 87 - 40 )

= 24 x 100

= 2400

    2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40

= ( 2 x 12 ) x 53 + ( 4 x 6 ) x 87 - ( 3 x 8 ) x 40

= 24 x 53 + 24 x 87 - 24 x 40

= 24  x ( 53 + 87 - 40 )

= 24 x 100

= 2400 

A = 4 . 2 . 25 . 5 . 175 

A = 2² . 2 . 5² . 5 . 5² . 7 

A = 2²⁺¹ . 5²⁺¹⁺² . 7  

A = 2³ . 5⁵ .7

A = 175000

\(B=4^2-10^4:\left(50\cdot273-50\cdot73\right)\)

\(B=4^2-10^4:\left[50\cdot\left(273-73\right)\right]\)

\(B=4^2-10^4:\left(50\cdot200\right)\)

\(B=4^2-10^4:10^4=4^2-1=15\)

\(C=3\times53\times6+2\times9\times87-18\times40\)

\(C=18\times53+18\times87-18\times40\)

\(C=18\times\left(53+87-40\right)\)

\(C=18\times100=1800\)

a, 2 x 31 x 12 + 4 x 6 x 42 + 8 x 27 x 3

= 2 x 12 x 31 + 4 x 6 x 42 + 8 x 3 x 27

= 24 x 31 + 24 x 42 + 24 x 27

= 24 x ( 31 + 24 + 27 )

= 24 x 82 

= 1968

b, 2 x 53 x 12 + 4 x 6 x 87 - 3 x 8 x 40

= 24 x 53 + 24 x 87 - 24 x 40

= 24 x ( 53 + 87 - 40 )

= 24 x 100

= 2400

c, Tương tự

a) = 1968

b) = 2400

đó là kq câu a) ; b)

**** Nha bn

2: \(=\dfrac{-2}{75}+\dfrac{5}{39}=\dfrac{33}{325}\)

3: \(=\dfrac{6}{11}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{6}{11}\)

4: \(=\dfrac{7}{19}\left(\dfrac{5}{13}+\dfrac{8}{13}-1\right)=-2\cdot\dfrac{7}{19}=-\dfrac{14}{19}\)

5: \(=\dfrac{2}{7}\left(\dfrac{4}{23}-\dfrac{27}{23}+1\right)=0\)

6: \(=\dfrac{3}{8}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\dfrac{11}{8}=\dfrac{3}{8}+\dfrac{11}{8}=\dfrac{14}{8}=\dfrac{7}{4}\)