\(\dfrac{x}{9}=\dfrac{4}{x}\)

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5 tháng 3 2022

\(\dfrac{x}{9}=\dfrac{4}{x}\\ \Rightarrow x^2=36\\ \Rightarrow x=\pm6\)

5 tháng 3 2022

\(\frac{x}{9}\)=\(\frac{4}{x}\)=>    \(^{x^2}\)=9.4 =36  => x =\(\sqrt{36}\)=6

6 tháng 5 2018

a)\(x.6=-72\)

=> x = -12

b)\(\dfrac{7}{3}:x=\dfrac{-11}{45}\)

=> \(x=\dfrac{-105}{11}\)

c) \(x=\dfrac{-17}{9}\)

d)\(x=\dfrac{-3}{17}\)

e) \(x=\dfrac{7}{6}\)

f) \(\dfrac{39}{7}:x=11\)

=> \(x=\dfrac{39}{77}\)

6 tháng 5 2018

a)

\(\dfrac{x}{8}=\dfrac{-9}{6}\)

=> x = \(\dfrac{8.\left(-9\right)}{6}\)

=> x = -12

9 tháng 4 2018

4,

a,\(\dfrac{x-1}{9}\)=\(\dfrac{8}{3}\)

[x- 1].3=9.8

[x- 1].3=72

x-1=72:3

x-1=24

x=24+1

x=25

17 tháng 4 2017

Giải bài 90 trang 43 SGK Toán 6 Tập 2 | Giải toán lớp 6

1 tháng 5 2018

Giải bà i 90 trang 43 SGK Toán 6 Tập 2 | Giải toán lá»p 6

17 tháng 4 2017

a) Thực hiện phép nhân ở vế phải rồi áp dụng quy tắc chuyển vế.

b) Thực hiện phép nhân ở về phải rồi quy đồng mẫu hai vế.

ĐS. a) ; b) x = -40.


19 tháng 4 2017

ko bt

23 tháng 4 2017

9) \(\dfrac{x}{4}=\dfrac{9}{x}\)

Theo định nghĩa về hai phân số bằng nhau, ta có:

\(4\cdot9=x^2\\ 36=x^2\Rightarrow\left[{}\begin{matrix}x=6\\x=-6\end{matrix}\right.\)

8)

\(x:\dfrac{5}{3}+\dfrac{1}{3}=-\dfrac{2}{5}\\ x:\dfrac{5}{3}=-\dfrac{2}{5}+\dfrac{1}{3}\\ x:\dfrac{5}{3}=-\dfrac{1}{15}\\ x=\dfrac{1}{15}\cdot\dfrac{5}{3}\\ x=\dfrac{1}{9}\)

7)

\(2x-16=40+x\\ 2x-x=40+16\\ x\left(2-1\right)=56\\ x=56\)

6)

\(1\dfrac{1}{2}+x=\dfrac{3}{2}-7\\ \dfrac{3}{2}+x=\dfrac{3}{2}-7\\ \dfrac{3}{2}-\dfrac{3}{2}=-7-x\\ -7-x=0\\ x=-7-0\\ x=-7\)

5)

\(3\dfrac{1}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\\ \dfrac{7}{2}-\dfrac{1}{2}x=\dfrac{2}{3}\\ \dfrac{1}{2}x=\dfrac{7}{2}-\dfrac{2}{3}\\ \dfrac{1}{2}x=\dfrac{17}{6}\\ x=\dfrac{17}{6}:\dfrac{1}{2}\\ x=\dfrac{17}{3}\)

4)

\(x\cdot\left(x+1\right)=0\Rightarrow\left[{}\begin{matrix}x=0\\x+1=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=0\\x=-1\end{matrix}\right.\)

3)

\(\left(\dfrac{2x}{5}+2\right):\left(-4\right)=-1\dfrac{1}{2}\\ \left(\dfrac{2x}{5}+2\right):\left(-4\right)=-\dfrac{3}{2}\\ \dfrac{2x}{5}+2=-\dfrac{3}{2}\cdot\left(-4\right)\\ \dfrac{2x}{5}+2=6\\ \dfrac{2x}{5}=6-2\\ \dfrac{2x}{5}=4\\ 2x=4\cdot5\\ 2x=20\\ x=20:2\\ x=10\)

2)

\(\dfrac{1}{3}+\dfrac{1}{2}:x=-0,25\\ \dfrac{1}{3}+\dfrac{1}{2}:x=-\dfrac{1}{4}\\ \dfrac{1}{2}:x=-\dfrac{1}{4}-\dfrac{1}{3}\\ \dfrac{1}{2}:x=-\dfrac{7}{12}\\ x=\dfrac{1}{2}:-\dfrac{7}{12}\\ x=-\dfrac{6}{7}\)

1)

\(\dfrac{4}{3}+x=\dfrac{2}{15}\\ x=\dfrac{2}{15}-\dfrac{4}{3}x=-\dfrac{6}{5}\)

21 tháng 4 2017

tìm x a)
\(\dfrac{7}{2}\)-\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{4}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{4}\) + \(\dfrac{7}{2}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-5}{12}+\dfrac{7}{12}\)
\(\left(x+\dfrac{7}{10}\right)\): \(\dfrac{6}{5}\) = \(\dfrac{-12}{12}=1\)
\(x+\dfrac{7}{10}\)= 1 . \(\dfrac{6}{5}\)
*Rồi tự làm phần tt đi




20 tháng 4 2017

Mình ghi kết quả luôn nha bạn

8 tháng 8 2018

1) \(x:\dfrac{2}{3}=150\)

\(\Leftrightarrow x=150.\dfrac{2}{3}\)

\(\Leftrightarrow x=100\).

2) \(\dfrac{35}{9}:x=\dfrac{35}{6}\)

\(\Leftrightarrow x=\dfrac{35}{9}:\dfrac{35}{6}\)

\(\Leftrightarrow x=\dfrac{2}{3}\).

3) \(\dfrac{49}{7}:x=\dfrac{49}{5}\)

\(\Leftrightarrow x=\dfrac{49}{7}:\dfrac{49}{5}\)

\(\Leftrightarrow x=\dfrac{5}{7}\).

4) \(1-\left\{5\dfrac{4}{9}+x-7\dfrac{7}{18}\right\}:15\dfrac{3}{5}=0\)

\(\Leftrightarrow1-\left\{\dfrac{49}{9}+x-\dfrac{133}{18}\right\}:\dfrac{78}{5}=0\)

\(\Leftrightarrow\left\{\dfrac{-35}{18}+x\right\}:\dfrac{78}{5}=1-0\)

\(\Rightarrow\dfrac{-35}{18}+x=1.\dfrac{78}{5}\)

\(\Leftrightarrow\dfrac{-35}{18}+x=\dfrac{78}{5}\)

\(\Rightarrow x=\dfrac{1579}{90}\).

8 tháng 8 2018

Gọi a,b,c.. cho dễ nhé.Thớt vui tính quá, dấu phẩy cũng không viết hộ con dân =)))

a, \(x:\dfrac{2}{3}=150\)

\(\Leftrightarrow x=150.\dfrac{2}{3}\)

\(\Leftrightarrow x=100\)

Vậy...

b, \(\dfrac{35}{9}:x=\dfrac{35}{6}\)

\(\Leftrightarrow x=\dfrac{35}{9}:\dfrac{35}{6}\)

\(\Leftrightarrow x=\dfrac{2}{3}\)

Vậy...

c, \(\dfrac{49}{7}:x=\dfrac{49}{5}\)

\(\Leftrightarrow x=\dfrac{49}{7}:\dfrac{49}{5}\)

\(\Leftrightarrow x=\dfrac{5}{7}\) Vậy...

d, \(1-\left\{5\dfrac{4}{9}+x-7\dfrac{7}{18}\right\}:15\dfrac{3}{4}=0\)

\(\Leftrightarrow1-\left\{\dfrac{49}{9}+x-\dfrac{133}{18}\right\}:\dfrac{63}{4}=0\)

\(\Leftrightarrow1-\left\{x-\dfrac{35}{18}\right\}:\dfrac{63}{4}=0\)

\(\Leftrightarrow1-\left(\dfrac{\left(18x-35\right).4}{18.63}\right)=0\)

\(\Leftrightarrow1-\left(\dfrac{72x-140}{1134}\right)=0\)

\(\Leftrightarrow1-\dfrac{72x-140}{1134}=0\)

\(\Leftrightarrow\dfrac{1134-72x+140}{1134}=0\)

\(\Leftrightarrow1274-72x=0\)

\(\Leftrightarrow72x=1274\)

\(\Leftrightarrow x=\dfrac{637}{36}\)

Vậy...

26 tháng 3 2017

9) x=7

10) x=6

18 tháng 3 2018

a)\(x+\dfrac{3}{4}=\dfrac{1}{2}\\ x=\dfrac{1}{2}-\dfrac{3}{4}=\dfrac{2}{4}-\dfrac{3}{4}=-\dfrac{1}{4}\)

b)\(\dfrac{5}{3}.x=\dfrac{4}{7}\\ x=\dfrac{4}{7}:\dfrac{5}{3}=\dfrac{4}{7}.\dfrac{3}{5}=\dfrac{12}{35}\)

c)\(\dfrac{2}{3}:x=\dfrac{-1}{4}\\ x=\dfrac{2}{3}:\dfrac{-1}{4}=\dfrac{2}{3}.\left(-4\right)=-\dfrac{8}{3}\)

d)\(\dfrac{5}{9}-x=\dfrac{4}{3}\\ x=\dfrac{5}{9}-\dfrac{4}{3}=\dfrac{5}{9}-\dfrac{12}{9}=\dfrac{-7}{9}\)

e)\(x+\dfrac{4}{17}=\dfrac{2}{34}\\ x=\dfrac{1}{17}-\dfrac{4}{17}=\dfrac{-3}{17}\)

f)\(3\dfrac{4}{7}:x=11\\ x=\dfrac{25}{7}:11=\dfrac{25}{7}.\dfrac{1}{11}=\dfrac{25}{77}\)

a: \(=\dfrac{-28}{36}+\dfrac{15}{36}-\dfrac{26}{36}=\dfrac{-39}{36}=\dfrac{-13}{12}\)

b: \(=\dfrac{11}{9}\left(\dfrac{15}{4}-\dfrac{7}{4}-\dfrac{5}{4}\right)=\dfrac{11}{9}\cdot\dfrac{3}{4}=\dfrac{11}{12}\)

c: \(=15+\dfrac{9}{7}+6+\dfrac{2}{3}-5-\dfrac{5}{9}\)

\(=16+\dfrac{88}{63}=\dfrac{1096}{63}\)

d: \(=\dfrac{5}{6}-\dfrac{1}{3}+\dfrac{2}{18}\)

\(=\dfrac{15-6+2}{18}=\dfrac{11}{18}\)