\(a,\)\(x+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+...+\frac{4}{41.45}=-\frac{37}{45}\)

  \(x+\left(\frac{9-5}{5.9}+\frac{13-9}{9.13}+\frac{17-13}{13.17}+...+\frac{45-41}{41.45}\right)=-\frac{37}{45}\)

  \(x+\left(\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+....+\frac{1}{41}-\frac{1}{45}\right)-\frac{37}{45}\)

 \(x+\left(\frac{1}{5}-\frac{1}{45}\right)=-\frac{37}{45}\)

 \(x+\frac{8}{45}=-\frac{37}{45}\)

\(x=-\frac{37}{45}-\frac{8}{45}\)

\(x=-1\)

thế phần b, c đâu bạn

a) Ta có: \(\frac{x}{12}=\frac{y}{3}.\)

=> \(\frac{x}{12}=\frac{y}{3}\) và \(x-y=36.\)

Áp dụng tính chất dãy tỉ số bằng nhau ta được:

\(\frac{x}{12}=\frac{y}{3}=\frac{x-y}{12-3}=\frac{36}{9}=4.\)

\(\left\{{}\begin{matrix}\frac{x}{12}=4=>x=4.12=48\\\frac{y}{3}=4=>y=4.3=12\end{matrix}\right.\)

Vậy \(\left(x;y\right)=\left(48;12\right).\)

b)

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

⇒ \(\frac{5}{3}x=\frac{5}{7}-\frac{2}{3}\)

⇒ \(\frac{5}{3}x=\frac{1}{21}\)

⇒ \(x=\frac{1}{21}:\frac{5}{3}\)

⇒ \(x=\frac{1}{35}\)

Vậy \(x=\frac{1}{35}.\)

\(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)

⇒ \(\left(x-\frac{1}{2}\right)^3=\left(\frac{1}{3}\right)^3\)

⇒ \(x-\frac{1}{2}=\frac{1}{3}\)

⇒ \(x=\frac{1}{3}+\frac{1}{2}\)

⇒ \(x=\frac{5}{6}\)

Vậy \(x=\frac{5}{6}.\)

Có 1 câu bạn đăng mình làm ở dưới rồi mà.

Chúc bạn học tốt!

a)áp dụng tính chất dãy tỉ số bằng nhau ta có:

\(\frac{x}{12}=\frac{y}{3}=\frac{x-y}{12-3}=\frac{36}{9}=4\)

\(\)x/12=4 suy ra x=12.4=48

y/3=4 suy ra y=3.4 =12

b)\(\frac{2}{3}+\frac{5}{3}x=\frac{5}{7}\)

\(\frac{5}{3}x=\frac{5}{7}-\frac{2}{3}\)

\(\frac{5}{3}x=\frac{1}{21}\)

\(x=\frac{1}{21}:\frac{5}{3}\)

\(x=\frac{1}{35}\)

\(\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}\)

\(\left(\frac{2}{5}+x\right)=\frac{11}{12}-\frac{2}{3}\)

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

\(x=\frac{1}{4}-\frac{2}{5}\)

\(x=\frac{-3}{20}\)

\(\left|x-\frac{2}{5}\right|+\frac{3}{4}=\frac{11}{4}\)

\(\left|x-\frac{2}{5}\right|=\frac{11}{4}-\frac{3}{4}\)

\(\left|x-\frac{2}{5}\right|=2\)

suy ra x-2/5=2 hoac x-2/5=-2

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

\(x=\frac{12}{5}\)

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

\(x=\frac{-8}{5}\)

\(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)

\(\left(x-\frac{1}{2}\right)^3=\left(\frac{1}{3}\right)^3\)

\(x-\frac{1}{2}=\frac{1}{3}\)

\(x=\frac{1}{3}+\frac{1}{2}\)

\(x=\frac{5}{6}\)

a)tìm x,y biết:$\frac{x}{12}=\frac{y}{3}vàx-y=36$

Ta có : \(\dfrac{x}{12} = \dfrac{y}{3}\) \(\Rightarrow\) \(\dfrac{x-y}{12-3} = \dfrac{36}{9} = 4\)

b)tìm x biết:

$\frac{2}{3}+\frac{5}{3}x=\frac{5}{7}$

\(\Leftrightarrow\) \(\dfrac{5}{3}x = \dfrac{5}{7} - \dfrac{2}{3}\)

\(\Leftrightarrow\) \(\dfrac{5}{3}x = \dfrac{1}{21}\)

\(\Leftrightarrow\) \(x = \dfrac{1}{35}\)

$\frac{11}{12}-\left(\frac{2}{5}+x\right)=\frac{2}{3}$

\(\Leftrightarrow\) \(\dfrac{2}{5} +x\) = \(\dfrac{2}{3} - \dfrac{11}{12}\)

\(\Leftrightarrow\) \(\dfrac{2}{5} + x = \dfrac{-1}{4}\)

\(\Leftrightarrow\) \(x = \dfrac{-13}{20}\)

$\left|x-\frac{2}{5}\right|+\frac{3}{4}=\frac{11}{4}$

\(\Leftrightarrow\) \(x - \dfrac{2}{5} = 2\)

\(\Leftrightarrow\) \(x = \dfrac{8}{5}\)

${\left(x-\frac{1}{2}\right)}^3=\frac{1}{27}$

\(\Leftrightarrow\) \(x - \dfrac{1}{2} = \dfrac{1}{19683}\)

\(\Leftrightarrow\) \(x = \dfrac{19685}{39366}\)

x=1,281236109

x=1,281236109

chú bn hok tốt

\(x=\)\(1,281236109\)

\(\frac{-1}{4}-\frac{3}{4}:x=\frac{-11}{36}\)

\(\frac{3}{4}:x=\frac{-1}{4}-\frac{-11}{36}\)

\(\frac{3}{4}:x=\frac{1}{18}\)

\(x=\frac{3}{4}:\frac{1}{18}\)

\(x=13,5\)

~ Chúc học tốt ~

Ai ngang qua xin để lại 1 L - I - K - E

-1/4 - 3/4 : x = -11/36

   <=>   3/4 : x = -1/4 - -11/36

  <=>  3/4 : x = -1/4 + 11/36

  <=> 3/4 : x  = 1/18

  <=>         x  = 3/4 : 1/18

  <=>        x   = 27/2  

x=3/7 nha ban !!! K TUI NHA

X=3/7:5/7-3/11:5/11+3/13:5/13

+

1/2:5/4-1/3+1/4:5/6

=3/5-3/5+3/5 + 2/5-1/3+3/10

=3/5 +  11/10

=17/10

câu 3:x=9

câu 6:x=1

y=2

a) Ta có: \(\frac{x}{9}=\frac{-12}{27}\)

=> \(27.x=-12.9\)

=> \(27x=-108\)

=> \(x=108:27\)

=>\(x=4\)