A)    \(x-\dfrac{2}{3}=\dfrac{4}{5}\\ x=\dfrac{4}{5}+\dfrac{2}{3}\)

           \(x=\dfrac{22}{15}\)

b)\(\dfrac{7}{9}-x=\dfrac{1}{3}\\ x=\dfrac{7}{9}-\dfrac{1}{3}\\ x=\dfrac{4}{9}\)

C)\(x:\dfrac{2}{3}=\dfrac{9}{8}\\ x=\dfrac{9}{8}x\dfrac{2}{3}\\ x=\dfrac{3}{4}\)

Câu D đâu bạn:)?

A

A?

`a)1/7xx2/7+1/7xx5/7+6/7`

`=1/7xx(2/7+5/7)+6/7`

`=1/7xx1+6/7`

`=1/7+6/7=1`

`b)6/11xx4/9+6/11xx7/9-6/11xx2/9`

`=6/11xx(4/9+7/9-2/9)`

`=6/11xx9/9`

`=6/11`

Sorry nãy ghi thiếu.

`c)4/25xx5/8xx25/4xx24`

`=(4xx5xx25xx24)/(25xx8xx4)`

`=(4xx5xx24)/(4xx8)`

`=(5xx24)/8`

`=5xx3=15`

1/3 x 3/5 x 5/7 x 7/9 x 9/11

= 1 x 3 x 5 x 7 x 9/ 3 x 5 x 7 x 9 x 11

= 1 x 11

= 11

\(A=\frac{1}{3}x\frac{3}{5}x\frac{5}{7}x\frac{7}{9}x\frac{9}{11}\)

\(\Rightarrow A=\frac{1x3x5x7x9}{3x5x7x9x11}\)

\(\Rightarrow A=\frac{1}{11}\)

Vậy A = \(\frac{1}{11}\)

Bài này áp dụng cách trực tiêu của phân số nha!

Chúc em học tốt nhé!!!

có cần giải chi tiết k bạn

\(\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{2}{7}:\frac{3}{5}+\frac{10}{9}\)

\(\Rightarrow\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{2}{7}.\frac{5}{3}+\frac{10}{9}\)

\(\Rightarrow\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{10}{21}+\frac{10}{9}\)

\(\Rightarrow\frac{2}{3}:\frac{x}{5}+\frac{5}{7}=\frac{100}{63}\)

\(\Rightarrow\frac{2}{3}:\frac{x}{5}=\frac{100}{63}-\frac{5}{7}\)

\(\Rightarrow\frac{2}{3}:\frac{x}{5}=\frac{55}{63}\)

\(\Rightarrow\frac{x}{5}=\frac{2}{3}:\frac{55}{63}\)

\(\Rightarrow\frac{x}{5}=\frac{2}{3}.\frac{63}{55}\)

\(\Rightarrow\frac{x}{5}=\frac{42}{55}\)

\(\Rightarrow x=\frac{42.5}{55}=\frac{42}{11}\)

Nên ta chọn đáp án D là đáp án đúng! 

( trong bài có dấu . tức là dấu dấu nhân bn nhé )

2/3 : x/5 + 5/7 = 2/7 : 3/5 + 10/9

2/3 : x/5 + 5/7 = 10/21 + 10/9

2/3 : x/5 + 5/7 = 100/63

2/3 : x/5 = 100/63 - 5/7

2/3 : x/5 = 55/63

2/3 . 5/x= 55/63

=) 5/x = 55/63 : 2/3

=) 5/x = 55/42

ta có : a/b = c/d =) a.d=b.c

(=) 55.x = 5.42

      55.x = 210

=)        x = 210 : 55 = 42/11

vậy đáp án đúng là D

 chúc bn học tốt

Phần a là 0

Phần b là 5

Phần c là  6

Phần d là 1

Phần e là 0

a,8/3

b,1/5

c,17/135

d,2/3

e,5/2

a)\(\frac{8}{3}\)

b)\(\frac{1}{5}=0,2\)

c)\(\frac{17}{135}\)

d)\(\frac{2}{3}\)

e)\(\frac{5}{2}=2,5\)

a x+\(\frac{1}{2}\)=\(\frac{5}{7}\)

x=\(\frac{5}{7}\)-\(\frac{1}{2}\)

x=\(\frac{3}{14}\)

b \(\frac{25}{7}\)-x=\(\frac{8}{9}\)

x=\(\frac{25}{7}\)-\(\frac{8}{9}\)

x=\(\frac{169}{43}\)

c \(\frac{15}{11}\)*x=\(\frac{5}{3}\)

x=\(\frac{5}{3}\):\(\frac{15}{11}\)

x=\(\frac{11}{9}\)

D x*\(\frac{5}{12}\)=\(\frac{8}{9}\)

x=\(\frac{8}{9}\):\(\frac{5}{12}\)

x=\(\frac{32}{15}\)

a) \(x+\frac{1}{2}=\frac{5}{7}\)

\(x=\frac{5}{7}-\frac{1}{2}\)

\(x=\frac{10}{14}-\frac{7}{14}\)

\(x=\frac{3}{14}\)

b) \(\frac{25}{7}-x=\frac{8}{9}\)

\(x=\frac{25}{7}-\frac{8}{9}\)

\(x=\frac{225}{63}-\frac{56}{63}\)

\(x=\frac{169}{63}\)

c) \(\frac{15}{11}\cdot x=\frac{5}{3}\)

\(x=\frac{5}{3}:\frac{15}{11}\)

\(x=\frac{5}{3}\cdot\frac{11}{15}\)

\(x=\frac{11}{9}\)

d) \(x\cdot\frac{5}{12}=\frac{8}{9}\)

\(x=\frac{8}{9}:\frac{5}{12}\)

\(x=\frac{8}{9}\cdot\frac{12}{5}\)

\(x=\frac{32}{15}\)