Bài giải

a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)

\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)

b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)

\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)

c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)

d,  \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)

\(=1+1+1\)

\(=3\)

e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)

\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)

\(=1+1+1\)

\(=3\)

a, \(\frac{4}{5}-\frac{2}{3}+\frac{1}{5}-\frac{1}{3}\)

\(=\left(\frac{4}{5}+\frac{1}{5}\right)-\left(\frac{2}{3}+\frac{1}{3}\right)=1-1=0\)

b, \(\frac{2}{5}\text{ x }\frac{7}{4}-\frac{2}{5}\text{ x }\frac{3}{7}\)

\(=\frac{2}{5}\text{ x }\left(\frac{7}{4}-\frac{3}{7}\right)=\frac{2}{5}\text{ x }\frac{37}{28}=\frac{37}{70}\)

c, \(\frac{13}{4}\text{ x }\frac{2}{3}\text{ x }\frac{4}{13}\text{ x }\frac{3}{12}=\frac{13\text{ x }2\text{ x }4\text{ x }3}{4\text{ x }3\text{ x }13\text{ x }12}=\frac{1}{6}\)

d,  \(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\frac{3}{4}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)

\(=1+1+1\)

\(=3\)

e, \(\frac{2}{5}+\frac{6}{9}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{2}{5}+\frac{2}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{3}+\frac{1}{4}\)

\(=\frac{1}{5}\left(2+3\right)+\frac{1}{3}\left(2+1\right)+\frac{1}{4}\left(3+1\right)\)

\(=\frac{1}{5}\cdot5+\frac{1}{3}\cdot3+\frac{1}{4}\cdot4\)

\(=1+1+1\)

\(=3\)

a ,            =(4/5+1/5)-(2/3+1/3)=1-1=0

  b   ,            =2/5 x (7/4-3/7) =2/5 x 37/28 =74/140=37/70

c,             =13/4 x 2/3 x 13/4  x 2/3=26/12 x 26/12= 13/6 x 13/6 =13 x 13/6 x 6(gạch 13 trên tử thì tử còn 1 x 13,mẫu hết.) =1 x 13/1=13

d,               =3/4+6/7+19/32 +1/4+1/7 +13/32=(3/4+1/4 )+(6/7+1/7)+(19/32+13/32)=1+1+1=3

e,            =(2/5+3/5)+(2/3+1/3)+(3/4+1/4) [6/9 rút gọn thành 2/3] =1+1+1=3

a/4989   ;    b/11/4    ;c/59/9    ;d/7/24    

a, 1727 + [ 6993 : 111 + ( 848 - 95 ) ] x 4 - 2

 = 1727 + [         63     +       753    ] x 4 - 2

 = 1727 +                 816                  x 4 - 2

 = 1727 +                          3264             - 2

 =                     4991                              - 2

 =            4989

b, 75/100 + 18/21 + 19/32 + 1/4 + 3/21 + 13/32

 = 75/100 + 1/4 + ( 18/21 + 3/21 ) + ( 19/32 + 13/32 )

 = 75/100 + 25/100 +      21/21     +           32/32

 =       100/100        +          1        +              1

 = 1 + 1 + 1 = 3

c, 4 2/5 + 5 6/9 + 2 3/4 + 3/5 + 1/3 + 1/4

 = ( 4 2/5 + 3/5 ) + ( 2 3/4 + 1/4 ) + 5 6/9 + 1/3

 =          5           +            3          +  5 6/9 + 3/9

 =          5           +            3          +            6

 =     8 + 6 = 14

d,  3/4 + 25/36 - ( 4/9 + 13/18 + 1/72 )

 =   27/36 + 25/36 - ( 32/72 + 52/72 + 1/72 )

 =             52/36    - (       84/72        + 1/72 )

 =             52/36    -                85/72

 =            104/72 - 85/72

 =                   19/72 

a ) 

75/100 + 18/21 + 19/32 + 1/4 + 3/21 + 13/32

= 3/4 + 18/21 + 19/321 + 1/4 + 3/21 + 13/32

= ( 3/4 + 1/4 ) + ( 18/21 + 3/21 ) + ( 19/32 + 13/32 )

= 1 + 1 + 1 

= 3

b ) 

4 và 2/5 + 5 và 6/9 + 2 và 3/4 + 1/4 + 1/3 + 3/5

= 22/5 + 51/9 + 11/4 + 1/4 + 1/3 + 3/5 

= ( 22/5 + 3/5 ) + ( 51/9 + 1/3 ) + ( 11/4 + 1/4 )

= 25/5 + 54/9 + 12/4

= 5 + 6 + 3 

= 14

a)\(\frac{75}{100}+\frac{18}{21}+\frac{19}{32}+\frac{1}{4}+\frac{3}{21}+\frac{13}{32}=\frac{3}{4}+\frac{18}{21}+\frac{1}{4}+\frac{19}{32}+\frac{3}{21}+\frac{13}{32}\)

\(=\left(\frac{3}{4}+\frac{1}{4}\right)+\left(\frac{18}{21}+\frac{3}{21}\right)+\left(\frac{19}{32}+\frac{13}{32}\right)\)

\(=1+1+1=3\)

1, 3^4

2, 5^405

3, -20/3

4, 4

                                                                             KHÔNG BÍT ĐÚNG HAY KO =>HIHIHIHI

1a

75/100+18/21+19/32+1/4+3/21+13/32

= 3/4 +6/7+19/32+1/4+1/7+13/32

= (3/4+1/4)+(19/32+13/32)+(6/7+1/7)

= 1+1+1=3

1b

22/5+51/9+11/4+3/5+1/3+1/4

=22/5+17/3+11/4+3/5+1/3+1/4

=(22/5+3/5)+(17/3+1/3)+(11/4+1/4)

=25/5+18/3+12/4

=5+6+3

=14

toi khong 

c] 7 * x + 8 * x + 9 * x + .... + 100 * x = 1025

(7+8+9+...+100)*x=1025

Coi A= 7+8+...+100

Số các số hạng của A là:

(100-7):1+1=94 (số)

=>A=(100+7)*94:2=5029

Ta lại có:

5029*x=1025

=>x=1025:5019=1025/5019

a, \(x.\left(\frac{3}{2}+\frac{1}{4}-\frac{1}{2}\right)=x.\left(\frac{6}{4}+\frac{1}{4}-\frac{2}{4}\right)=\frac{10}{9}\)

   \(x.\frac{5}{4}=\frac{10}{9}\)

   \(x=\frac{10}{9}:\frac{5}{4}=\frac{10}{9}.\frac{4}{5}=\frac{8}{9}\)

a, 1+2+3+4+5+6+7+8+9+...+100

Tổng dãy số trên là :

\(\frac{100.\left(100+1\right)}{2}=5050\)

b, 23+54+32+67+100x0

= 23 + 54 + 32 + 67

= ( 23 + 67 ) + ( 54 + 32 )

= 90 + 86

= 176

Study well 

a, ko ghi đề

=(100+1)+(99+2)+...+(50+51) ( có 50 cặp )

=(101) x 50

=5050

b,ko ghi đề nốt

=(23+54+32+67)+0

=176

Nhớ k đúng mk nha ^^

a) 1 + 2 + 3 + 4 +...+ 100 có: ( 100 - 1 ) : 1 + 1 = 100 ( số hạng )

=> 1 + 2 + 3 + 4 +...+ 100 = ( 100 + 1 ) x 100 : 2 = 5050.

b) 23 + 54 + 32 + 67 + 100 x 0

= 23 + 54 + 32 + 67 

= ( 23 + 67 ) + 54 + 32

= 90 + 54 + 32

= 144 + 32

= 176