g: =900x13

=11700

a)184 x 72 + 184 x 27 + 184

=184 x 72 + 184 x 27 + 184 x 1

= 184 x (72 + 27 + 1 )

=184 x 100=18400

c)1999 x 346 + 1999 + 653 x 1999

=1999 x 346 + 1999 + 653 x 1999 x 1

= 1999 x ( 346 + 653 + 1 )

= 1999 x 1000=1999000

e)23 x 5 x 7 x 4

= ( 23 x 7) x( 5 x 4)

= 161 x 20= 3220

b)1996 x 1257 – 1996 – 256 x 1996

=1996 x 1257 – 1996 – 256 x 1996 x 1

= 1996 x ( 1257 - 256 - 1 )

= 1996 x 1000= 1996000

a ) 184 x 72 +184 x 27 + 184 
 = 184 x ( 72 + 27 ) + 184
 = 184 x 99 + 184 
 = 18216 + 184
 = 18400
c) 1999 x 346 + 1999 + 653 x 1999
 = 1999 x ( 346 + 653 ) + 1999
 = 1999 x 999 + 1999
 = 1997001 + 1999 
 = 1999000
 e)  23 x 5 x 7 x 4
 = 23 x 7 x 5 x 4
 = 161 x 20
 = 3220
 b) 1996 x 1257 -1996 - 256 x 1996
 = 1996 x ( 1257 - 256 ) - 1996
 = 1996 x 1001 - 1996 
 = 1997996 - 1996
 = 1996000
 d) 24 x 89 + 24 + 16 x 15
 = 24 x 89 + 16 x 15 + 24
 = 2136 + 240 + 24
 = 2400
 g) 25 x 36 x 13
 = 25 x 36 x 13
 = 900 x 13
 = 11700
                                                        bài này làm hơi lâu nhưng khá dễ lần sau bạn nên tự
                                                       làm nha ♥♥

a)

`1/3+3/4+2/3+1/4`

`=1/3+2/3+3/4+1/4`

`=1+1`

`=2`

b)

`3/4+3/5+2/8+4/10`

`=3/4+2/8+3/5+4/10`

`=6/8+2/8+6/10+4/10`

`=1+1`

`=2`

c)

`1/10+2/10+3/10+4/10+5/10+6/10+7/10+8/10+9/10`

`=1/10+9/10+2/10+8/10+3/10+7/10+6/10+4/10+5/10`

`=1+1+1+1+5/10`

`=4+5/10`

`=40/10+5/10`

`=45/10=9/2`

a: =1/3+2/3+3/4+1/4

=1+1

=2

b: =3/4+1/4+3/5+2/5

=1+1

=2

c: =(1+2+3+4+5+6+7+8+9)/10

=45/10

=9/2

\(a,13\dfrac{3}{5}-\left(8\dfrac{3}{5}-4\dfrac{3}{4}\right)\)

\(=\dfrac{68}{5}-\dfrac{43}{5}+\dfrac{19}{4}\)

\(=5+\dfrac{19}{4}\)

\(=\dfrac{20}{4}+\dfrac{19}{4}=\dfrac{39}{4}\)

\(------\)

\(b,11\dfrac{1}{4}-\left(2\dfrac{5}{7}+5\dfrac{1}{4}\right)\)

\(=\dfrac{45}{4}-\dfrac{19}{7}-\dfrac{21}{4}\)

\(=\left(\dfrac{45}{4}-\dfrac{21}{4}\right)-\dfrac{19}{7}\)

\(=6-\dfrac{19}{7}\)

\(=\dfrac{42}{7}-\dfrac{19}{7}=\dfrac{23}{7}\)

a: \(=\dfrac{17}{7}+\dfrac{2}{9}-\dfrac{10}{7}-\dfrac{5}{3}\cdot9=1+\dfrac{2}{9}-15=-14+\dfrac{2}{9}=-\dfrac{126}{9}+\dfrac{2}{9}=-\dfrac{124}{9}\)

b: \(=\dfrac{-11}{23}\left(\dfrac{6}{7}+\dfrac{8}{7}\right)-\dfrac{1}{23}=\dfrac{-22}{23}-\dfrac{1}{23}=-1\)

c: \(=\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\dfrac{4-3-1}{24}=0\)

d: \(=\dfrac{12}{7}\left(19+\dfrac{5}{8}-15-\dfrac{1}{4}\right)=\dfrac{12}{7}\cdot\dfrac{35}{8}=\dfrac{15}{2}\)

Ta có: \(A=\left(1-\dfrac{1}{2}\right)\left(1-\dfrac{1}{3}\right)\left(1-\dfrac{1}{4}\right)\cdot...\cdot\left(1-\dfrac{1}{9}\right)\)

\(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot\dfrac{4}{5}\cdot...\cdot\dfrac{8}{9}\)

\(=\dfrac{1}{9}\)

a.\(\frac{3}{5}\)\(.\)\(\frac{1195}{1999}\)+ \(\frac{4}{1999}\)\(.\)\(\frac{3}{5}\)= \(\frac{3}{5}.\left(\frac{1195}{1999}+\frac{4}{1999}\right)\)= \(\frac{3}{5}.1\)= \(\frac{3}{5}\)

b. \(\frac{2}{3}\)\(:\)\(\frac{5}{7}\)\(.\)\(\frac{5}{7}\)\(:\)\(\frac{2}{3}\)\(+1934\)= \(\frac{2}{3}\).\(.\)\(\frac{7}{5}\)\(.\)\(\frac{5}{7}\)\(.\)\(\frac{3}{2}\)\(+\)\(1934\)= \(1\)\(+\)\(1934\)= \(1935\)

a] 3/5 . (1195/1999+4/1999)=tự tính

b] (2/3:2/3) . (5/7:5/7) + 1934=tự tính

Sr nha, mình bt làm hai câu đầu thôi.

 câu b bài 2 thiếu nha e

B1

a, 638 +780 x 5 - 369 : 9 = 4497 

b, ( 273 + 485 ) x16 - 483 :3 x4 = 11484 

B2

a, 325 x 6 + 6 x 560 + 115 = 5425

B3

a, x = 1020

b, x = 36

B4

26 nha

ta có số cần tìm là xy , số mới là 5xy ( lưu ý là 5xy và xy là số )

5xy : xy = 26

ta có : 5x : 26 = 2 ( vì nếu ko sẽ ko ra k quả có số đầu là 5 ) 

 26 x 2 = 52

=> 52 - 52 hết và x = 2

y : 26 = 0 ( vì y < 26 )

=> ta có y= 0 

vậy số cần tìm là : xy = 20 

a) \(\left(\dfrac{3}{29}-\dfrac{1}{5}\right)\cdot\dfrac{29}{3}\)

\(=\dfrac{3}{29}\cdot\dfrac{29}{3}-\dfrac{1}{5}\cdot\dfrac{29}{3}\)

\(=1-\dfrac{29}{15}\)

\(=\dfrac{15-29}{15}\)

\(=-\dfrac{14}{15}\) 

b) \(\dfrac{3}{4}\cdot\dfrac{7}{9}+\dfrac{1}{4}\cdot\dfrac{7}{9}\)

\(=\dfrac{7}{9}\cdot\left(\dfrac{1}{4}+\dfrac{3}{4}\right)\)

\(=\dfrac{7}{9}\cdot1\)

\(=\dfrac{7}{9}\)

c) \(\dfrac{1}{7}\cdot\dfrac{5}{9}+\dfrac{5}{9}\cdot\dfrac{1}{7}+\dfrac{5}{9}\cdot\dfrac{3}{7}\) 

\(=\dfrac{5}{9}\cdot\left(\dfrac{1}{7}+\dfrac{1}{7}+\dfrac{3}{7}\right)\)

\(=\dfrac{5}{9}\cdot\dfrac{5}{7}\)

\(=\dfrac{25}{63}\)

d) \(4\cdot11\cdot\dfrac{3}{4}\cdot\dfrac{9}{121}\)

\(=\left(4\cdot\dfrac{3}{4}\right)\cdot\left(11\cdot\dfrac{9}{121}\right)\)

\(=3\cdot\dfrac{9}{11}\)

\(=\dfrac{27}{11}\)

a) \(A=1+\left(-3\right)+5+\left(-7\right)+...+\left(-1999\right)+2001\)

Số số hạng của tổng trên là: \(\frac{2001-1}{2}+1=1001\).

\(A=\left[1+\left(-3\right)\right]+\left[5+\left(-7\right)\right]+...+\left[1997+\left(-1999\right)\right]+2001\)

\(A=-2.500+2001\)

\(A=1001\)

b) \(1+\left(-2\right)+\left(-3\right)+4+5+\left(-6\right)+\left(-7\right)+8+...+1997+\left(-1998\right)+\left(-1999\right)+2000\)

\(=\left\{\left[1+\left(-2\right)\right]+\left[\left(-3\right)+4\right]\right\}+...+\left\{\left[1997+\left(-1998\right)\right]+\left[\left(-1999\right)+2000\right]\right\}\)

\(=\left(-1+1\right)+\left(-1+1\right)+...+\left(-1+1\right)\)

\(=0+0+...+0=0\)