a: Sửa đề: \(16\left(38-2\right)-38\left(16-2\right)\)

\(=16\cdot38-16\cdot2-38\cdot16+38\cdot2=22\cdot2=44\)

b: \(=-25\cdot75+25\cdot45-75\cdot45+75\cdot25\)

\(=25\cdot45-75\cdot45\)

\(=45\cdot\left(-50\right)=-2250\)

35 . 34 + 35 . 38 + 65 . 75 + 65 . 45 + 35 . 34 = 

= 35 . 34 + 35 . 38 + 35 . 34 + 65 . 75 + 65 . 45 

= 35 . ( 34 + 38 + 34 ) + 65 . ( 75 + 45 )

=  35 . 110  + 65 . 110 

= 110 . ( 35 + 65 ) 

= 110 . 100

= 11000

Hok tốt!!!!!!!!!!!!!

a) Tính bằng cách hợp lí nhất :

35 . 34 + 35 . 38 + 65 . 75 + 65 . 45 + 35 . 34

= 35 . 34 + 35 . 38 + 35 . 34 + 65 . 75 + 65 . 45

= 35 . ( 34 + 38 + 34 ) + 65 . ( 75 + 45 )

= 35 . 106 + 65 . 120

= 3710 + 7800

= 11510

3 . 25 . 8 + 4 . 37 . 6 + 2 . 38 . 12

= 3 . 8 . 25 + 4 . 6 . 37 + 2 . 12 . 38

= 24 . 25 + 24 . 37 + 24 . 38

= 24 . ( 25 + 37 + 38 )

= 24 . 100

= 2400

b) Tìm số tự nhiên x, biết :

( x - 5 ) ( x + 7 ) = 0

\(\Rightarrow\orbr{\begin{cases}x-5=0\\x+7=0\end{cases}\Rightarrow\orbr{\begin{cases}x=5\\x=-7\end{cases}}}.\)

Vậy .......

3 . 25 . 8 + 4 . 37 . 6 + 2 . 38 . 12 = 

= 3 . 8 . 25 +  4 . 6 . 37 + 2 . 12 . 38

= 24 . 25 + 24 . 37 + 24 . 38

= 24 . ( 25 + 37 + 38 )

= 24 . 100 

= 2400

Hok tốt!!!!!!!!!!!

a ) - 24

B ) - 65

a) \(-524\cdot\left[23+\left(-45\right)\right]+524\cdot\left(-45+123\right)\)

\(=-524\cdot\left[\left(23-45\right)-\left(-45+123\right)\right]\)

\(=-524\cdot\left(23-45+45-123\right)\)

\(=-524\cdot-100\)

\(=52400\)

b) \(47\cdot69-31\cdot\left(-47\right)\)

\(=-47\cdot\left(-69-31\right)\)

\(=-47\cdot-100\)

\(=4700\)

c) \(16\left(38-2\right)-38\left(16-1\right)\)

\(=16\cdot38-16\cdot2-38\cdot16+38\)

\(=-16\cdot2+38\)

\(=-36+38\)

\(=2\)

d) \(\left(-41\right)\cdot\left(59+2\right)+59\cdot\left(41-2\right)\)

\(=-41\cdot59-41\cdot2+41\cdot59-2\cdot59\)

\(=-41\cdot2-2\cdot59\)

\(=-2\left(41+59\right)\)

\(=-2\cdot100\)

\(=-200\)

e) \(25\cdot\left(-8\right)\cdot\left(-25\right)\cdot9\cdot4\cdot100^0:3\)

\(=\left(-1000\right)\cdot\left(-25\right)\cdot9\cdot4\cdot1:3\)

\(=25000\cdot9\cdot4:3\)

\(=25000\cdot3\cdot4\)

\(=100000\cdot3\)

\(=300000\)

a)524.[23+(-45)] + 524.(-45+123)

=524.(-22) + 524.78

=524.(-22+78)

=524.100

=52400

a)      29 + 132 + 237 + 868 + 763

    =  ( 132 + 868 ) + ( 237 + 763 ) + 29

    = 1000 + 1000 + 29

    =  1000 x 2 + 29

    =  2000 + 29

    =  2029

b)    35 x 34 + 35 x 38 + 65 x 75 + 45

    =  35 x ( 34 + 38 ) + 65 x 75 + 45

    =  35 x 72 + 65 x 75 + 45

    =  2520 + 4875 + 45

    =  2520 + 4920

    =  7440

c)     3 x 25 x 8 + 4 x 37 x 6 + 2 x 38 x 12

    =  ( 3 x 8 ) x 25 + ( 4 x 6 ) x 37 + ( 2 x 12 ) x 38

    =   24 x 25 + 24 x 37 + 24 x 38

    =   24 x ( 25 + 37 + 38 )

    =   24 x 100

    =   2400

a)29+132+237+868+763

=(132+868)+(237+763)+29

=     1000   +   1000    +29

=      2029

a,29+132+237+868+763

=29+(132+868)+(237+763)

=29+1000+1000

=2029

a. (-7).(-3).17.(-1)²

= (-7).(-3).17.1

= 21.17.1

=357.1

=357