a. x + \(\dfrac{3}{7}\)= \(\dfrac{2}{5}:\dfrac{18}{25}=>x+\dfrac{3}{7}=\dfrac{2}{5}\)x\(\dfrac{35}{18}=>x+\dfrac{3}{7}=\dfrac{7}{9}\)

=> x = \(\dfrac{7}{9}-\dfrac{3}{7}=\dfrac{49}{63}-\dfrac{27}{63}=\dfrac{22}{63}\)

b. \(x\) x \(\dfrac{5}{9}\)= \(\dfrac{4}{5}-\dfrac{1}{3}\)

=> \(x\) x \(\dfrac{5}{9}\)= \(\dfrac{12}{15}-\dfrac{5}{15}=>x\) x \(\dfrac{5}{9}\)= \(\dfrac{7}{15}\)

=> x = \(\dfrac{7}{15}:\dfrac{5}{9}\)

=> x = \(\dfrac{21}{25}\)

a,x + 3/7 = 2/5 : 18/35

   x + 3/7 = 7/9

   x          = 7/9 - 3/7

   x          = 22/63

vậy x = ...

b, X x 5/9 = 4/5 - 1/3

    X x 5/9 = 7/15

            X  = 7/15 : 5/9

            X  = 21/25

vậy X = ...

\(a.x+\dfrac{3}{7}=\dfrac{2}{5}:\dfrac{18}{35}\\x+\dfrac{3}{7}=\dfrac{2}{5}\times\dfrac{35}{18} \\ x+\dfrac{3}{7}=\dfrac{7}{9}\\ x=\dfrac{7}{9}-\dfrac{3}{7}\\ x=\dfrac{22}{63}\)

\(b.x\times\dfrac{5}{9}=\dfrac{4}{5}-\dfrac{1}{3}\\x\times\dfrac{5}{9}=\dfrac{7}{15}\\ x=\dfrac{7}{15}:\dfrac{5}{9}\\ x= \dfrac{21}{25}\)

mk đã giải cho bạn rồi nhé! bạn xem lại phần thông báo ạ!

=> 4x . 2 = 3y . 5

8x = 15y

=> x = 15; y = 8

T.I.C.K GIÚP MK NHÉ!

Ta có : \(\frac{x}{5}=\frac{y}{6};\frac{y}{8}=\frac{z}{11}\)

+) \(\frac{x}{5}=\frac{y}{6}\Rightarrow\frac{x}{40}=\frac{y}{48}\)(1)

+) \(\frac{y}{8}=\frac{z}{11}\Rightarrow\frac{y}{48}=\frac{z}{66}\)(2)

Từ (1) và (2) => \(\frac{x}{40}=\frac{y}{48}=\frac{z}{66}\)

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

\(\frac{x}{40}=\frac{y}{48}=\frac{z}{66}=\frac{x+y-z}{40+48-66}=\frac{44}{22}=2\)

=> \(\hept{\begin{cases}\frac{x}{40}=2\\\frac{y}{48}=2\\\frac{z}{66}=2\end{cases}}\Rightarrow\hept{\begin{cases}x=80\\y=96\\z=132\end{cases}}\)

Lại có : A = x - y - 2z = 80 - 96 - 2.132 = -280

Vậy A = -280

Ta có :\(\frac{x^7+x^6+x^5+x^4+x^3+x^2+1}{x^2-1}\)

\(=\frac{x^6\left(x+1\right)+x^4\left(x+1\right)+x^2\left(x+1\right)+\left(x+1\right)}{x^2-1}\)

\(=\frac{\left(x^6+x^4+x^2+1\right)\left(x+1\right)}{\left(x-1\right)\left(x+1\right)}\)

\(=\frac{\left(x^6+x^4+x^2+1\right)}{\left(x-1\right)}\)

Ta có : \(\frac{5}{7}=\frac{x}{63}\)

\(\Rightarrow\)   \(\frac{45}{63}=\frac{x}{63}\)

\(\Rightarrow\)    \(x=45\)

Vậy x = 45

                       Cbht !!! ❤️❤️❤️ 

\(\frac{5}{7}=\frac{x}{63}\\ \Leftrightarrow5\times63=7x.\)

\(\Leftrightarrow315=7x\)

\(\Leftrightarrow x=45\)

5/7 = x/63

5/7=x:9/63:9

5/7=x:9/7

x=5