a,3/7+4/5+4/7.

= ( 3/7 + 4/7 ) + 4/5 

= 1 + 4/5 

= 9/5 

b,6/11+1/3+5/11

= ( 6/11 + 5/11 ) + 1/3 

= 1 + 1/3 

= 4/3

#hien#

a,3/7+4/5+4/7.

= ( 3/7 + 4/7 ) + 4/5 

= 1 + 4/5 

= 9/5 

b,6/11+1/3+5/11

= ( 6/11 + 5/11 ) + 1/3 

= 1 + 1/3 

= 4/3

*Ryeo*

(6 x 5 + 7 - 37) x ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

= (30 + 7 - 37) x ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

=       0           x ( 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

=       0

 Haibara Ai

(6x5+7-37)=0 vì 30+7=37-37=0

Mà khi có một số tự nhiên nào nhân với 0 thì tích đó là 0

Vậy tích đó bằng 0

a) \(x-\frac{4}{9}=\frac{5}{6}\)

 \(\Leftrightarrow\frac{18x}{18}-\frac{8}{18}=\frac{15}{18}\)

\(\Rightarrow18x-8=15\)

\(\Leftrightarrow18x=15+8\)

\(\Leftrightarrow18x=23\)

\(\Leftrightarrow x=\frac{23}{18}\)

Vậy \(x=\frac{23}{18}\)

b)\(x-7=\frac{1}{6}\)

\(\Leftrightarrow\frac{6x}{6}-\frac{42}{6}=\frac{1}{6}\)

\(\Rightarrow6x-42=1\)

\(\Leftrightarrow6x=42+1\)

\(\Leftrightarrow6x=43\)

\(\Leftrightarrow x=\frac{43}{6}\)

Vậy \(x=\frac{43}{6}\)

c)\(x-\frac{7}{8}=11\)

\(\Leftrightarrow\frac{8x}{8}-\frac{7}{8}=\frac{88}{8}\)

\(\Rightarrow8x-7=88\)

\(\Leftrightarrow8x=88+7\)

\(\Leftrightarrow8x=95\)

\(\Leftrightarrow x=\frac{95}{8}\)

Vậy \(x=\frac{95}{8}\)

#bn cs thể bỏ\(\Leftrightarrow;\Rightarrow\)đều đc nhé #

 #hoktot<3# 

a, x - 4/9 = 5/6 

         x   =  5/6 + 4/9

         x   =    69/54

b, x - 7 = 1/6

        x  =  1/6 + 7 

        x =  43/6

 c, x - 7/8 = 11 

          x    = 11 + 7/8 

           x   =  95/8

A) x - 4/9 = 5/6 

    x          = 5/6 + 4/9 

   x           =  23/18

 B) x - 7 = 1/6 

    x.      = 1/6 + 7 

  x.       = 43/6 

 C) x - 7/8 = 11 

    x.         = 11 + 7/8 

   x.         = 95/8

#hien#

giúp mik zứi😭😭😭

a; 60 \(\times\) (\(\dfrac{7}{12}\) + \(\dfrac{4}{15}\)) 

 =  60 \(\times\) \(\dfrac{7}{12}\) + 60 \(\times\) \(\dfrac{4}{15}\)

= 35 + 16

= 51

b; \(\dfrac{1}{2}\) \(\times\)\(\dfrac{2}{3}\) \(\times\) \(\dfrac{3}{4}\) \(\times\) \(\dfrac{4}{5}\) \(\times\) \(\dfrac{5}{6}\) \(\times\) \(\dfrac{7}{8}\) \(\times\) \(\dfrac{8}{9}\)

= \(\dfrac{2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8}\) \(\times\) \(\dfrac{1}{9}\)

= 1 \(\times\) \(\dfrac{1}{9}\)

= \(\dfrac{1}{9}\)

\(\frac{2}{6}+\frac{9}{24}\)

\(=\frac{8}{24}+\frac{9}{24}\)

\(=\frac{17}{24}\)

Tương Tự vs các câu còn lại 

\(\frac{7}{2}+\frac{1}{3}-\frac{5}{2}\)

\(=\left(\frac{7}{2}-\frac{5}{2}\right)+\frac{1}{3}\)

\(=1+\frac{1}{3}\)

\(=\frac{4}{3}\)

a, MSC : 24

   5/8 = 5 x 3/ 8 x 3 = 15/24

   7/12 = 7 x 2/ 12 x 2 = 14/24

b, MSC : 60

  17/15 = 17 x 4/ 15 x 4 = 68/ 60

  29/20 = 29 x 3/ 20 x 3 = 87/ 60

c, MSC : 12

   5/6 = 5 x 2/ 6 x 2 = 10/12

   3/4 = 3 x 3/ 4 x 3 = 9/12

d, MSC : 84

   4/7 = 4 x 12/ 7 x 12 = 48/84

   7/12 = 7 x 7/ 12 x 7 = 49/84

cho mik nha!

Mik cảm ơn!

cho mik nha

cho rùi.

\(A=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{9.11}-\frac{1}{11.13}\)

\(\Leftrightarrow A=\frac{1}{1.3}-\frac{1}{11.13}=\frac{1}{3}-\frac{1}{143}=\frac{140}{429}\)

\(A=\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+\frac{4}{7.9.11}+\frac{4}{9.11.13}\)

\(\Rightarrow A=\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+...+\frac{1}{9.11}-\frac{1}{11.13}\)

\(\Rightarrow A=\frac{1}{1.3}-\frac{1}{11.13}=\frac{1}{3}-\frac{1}{143}=\frac{140}{429}\)

A =\(\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+\frac{4}{7.9.11}+\frac{4}{9.11.13}\)

   = \(\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+\frac{1}{5.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.11}+\frac{1}{9.11}-\frac{1}{11.13}\)

   = \(\frac{1}{1.3}-\frac{1}{11.13}\)

   = \(\frac{1}{3}-\frac{1}{143}\)

  = \(\frac{140}{429}\)

Dấu "." là dấu nhân

A=1                                                                                                                                                                                                  B=-4