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17 tháng 5 2016

a)\(\frac{4}{5}\times\frac{8}{3}\times\frac{x}{7}=\frac{96}{105}\)

\(\frac{x}{7}=\frac{96}{105}:\frac{4}{5}:\frac{8}{3}=\frac{3}{7}\)

\(x=3\)

b) \(\frac{7}{4}\times\frac{3}{x}\times\frac{11}{5}=\frac{231}{200}\)

\(\frac{3}{x}=\frac{231}{200}:\frac{7}{4}:\frac{11}{5}=\frac{3}{10}\)

\(x=10\)

29 tháng 5 2020

A. \(\frac{4}{5}\times\frac{8}{3}\times\frac{x}{7}=\frac{96}{105}\)

=\(\frac{4}{5}\times\left(\frac{8}{3}\times\frac{x}{7}\right)=\frac{96}{105}\)

\(\frac{8}{3}\times\frac{x}{7}=\frac{96}{105}\div\frac{4}{5}\)

\(\frac{8}{3}\times\frac{x}{7}=\frac{480}{420}=\frac{8}{7}\)

=\(\frac{x}{7}=\frac{8}{7}\div\frac{8}{3}\)

\(X=\frac{24}{56}=\frac{3}{7}\)

\(X=3\)

@Moon

a)\(\frac{4}{5}\cdot\frac{8}{3}\cdot\frac{x}{7}=\frac{96}{105}\)

\(\frac{4}{5}\cdot\frac{8}{3}\cdot\frac{x}{7}=\frac{32}{35}\)

\(\frac{4\cdot8\cdot x}{5\cdot3\cdot7}=\frac{32}{35}\)

\(\frac{32\cdot x}{105}=\frac{32}{35}\)

\(\Rightarrow32\cdot x\cdot35=32\cdot105\)( chỗ này là nhân tích chéo nha )

\(\Rightarrow x\cdot35=105\)

\(x=105:35\)

\(x=3\)Vậy x=3

b)\(\frac{7}{4}\cdot\frac{3}{x}\cdot\frac{11}{5}=\frac{231}{200}\)

\(\frac{7\cdot3\cdot11}{4\cdot x\cdot5}=\frac{231}{200}\)

\(\frac{231}{20\cdot x}=\frac{231}{200}\)

\(\Rightarrow20\cdot x=200\)

\(x=200:20\)

\(x=10\)Vậy x=10

1 tháng 3 2018

a) \(\frac{4}{5}\times\frac{8}{3}\times\frac{x}{7}=\frac{96}{105}\)

\(\frac{32}{15}\times\frac{x}{7}=\frac{32}{35}\)

\(\frac{x}{7}=\frac{32}{35}:\frac{32}{15}\)

\(\frac{x}{7}=\frac{3}{7}\)

\(\Rightarrow x=3\)

b) \(\frac{7}{4}\times\frac{3}{x}\times\frac{11}{5}=\frac{231}{200}\)

\(\frac{7}{4}\times\frac{11}{5}\times\frac{3}{x}=\frac{231}{200}\)

\(\frac{77}{20}\times\frac{3}{x}=\frac{231}{200}\)

\(\frac{3}{x}=\frac{231}{200}:\frac{77}{20}\)

\(\frac{3}{x}=\frac{3}{10}\)

\(\Rightarrow x=10\)

CHÚC BẠN HỌC TỐT!!!!!!!!!!

8 tháng 9 2021

a)4/3:x=-4/7                         b)5/3.x=7/12

⇒x=-16/21                             ⇒x=7/20

8 tháng 9 2021

a. \(\dfrac{5}{7}+\dfrac{4}{3}:x=\dfrac{1}{7}\)

<=> \(\dfrac{5}{7}+\dfrac{4}{3}.\dfrac{1}{x}=\dfrac{1}{7}\)

<=> \(\dfrac{5}{7}+\dfrac{4}{3x}=\dfrac{1}{7}\)         ĐKXĐ: x \(\ne\) 0

<=> \(\dfrac{15x}{21x}+\dfrac{28}{21x}=\dfrac{3x}{21x}\)

<=> 15x + 28 = 3x

<=> 15x - 3x = -28

<=> 12x = -28

<=> x = \(\dfrac{-28}{12}=-\dfrac{7}{3}\)

b. \(\dfrac{5}{3}x.\dfrac{-1}{4}=\dfrac{2}{6}\)

<=> \(\dfrac{-5x}{12}=\dfrac{2}{6}\)

<=> -5x . 6 = 12 . 2

<=> -30x = 24

<=> x = \(-\dfrac{4}{5}\)

7 tháng 3 2022

\(a,x-\dfrac{1}{4}=\dfrac{7}{2}.\dfrac{-3}{5}\\ \Rightarrow x-\dfrac{1}{4}=\dfrac{-21}{10}\\ \Rightarrow x=\dfrac{-21}{10}+\dfrac{1}{4}\\ \Rightarrow x=\dfrac{-37}{20}\\ b,\dfrac{x}{134}=\dfrac{9}{7}.\dfrac{5}{-11}\\ \Rightarrow\dfrac{x}{134}=\dfrac{-45}{77}\\ \Rightarrow x=\dfrac{-45}{77}.134\\ \Rightarrow x=\dfrac{-6030}{77}\)

7 tháng 3 2022

\(x-\dfrac{1}{4}=\dfrac{7}{2}\cdot\dfrac{-3}{5}\)

\(x-\dfrac{1}{4}=\dfrac{-21}{10}\)

\(x=\dfrac{-21}{10}+\dfrac{1}{4}\)

\(x=\dfrac{-37}{20}\)

b ) \(\dfrac{x}{134}=\dfrac{9}{7}\cdot\dfrac{5}{-11}\)

      \(\dfrac{x}{134}=\dfrac{9}{7}\cdot\dfrac{-5}{11}\)

       \(\dfrac{x}{134}=\dfrac{-45}{77}\)

       \(x=\dfrac{-45}{77}\cdot134\)

       \(x=-\dfrac{6034}{77}\)

4 tháng 9 2021

a) \(\left(3x+5\right)\left(7-2x\right)+6x\left(x+4\right)=0\)

\(\Leftrightarrow21x-6x^2+35-10x+6x^2+24x=0\)

\(\Leftrightarrow35x=-35\Leftrightarrow x=-1\)

b) \(x^3-25x=0\)

\(\Leftrightarrow x\left(x^2-25\right)=0\)

\(\Leftrightarrow x\left(x-5\right)\left(x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=5\\x=-5\end{matrix}\right.\)

a: Ta có: \(\left(3x+5\right)\left(7-2x\right)+6x\left(x+4\right)=0\)

\(\Leftrightarrow21x-6x^2+35-10x+6x^2+24x=0\)

\(\Leftrightarrow x=1\)

b: Ta có: \(x^3-25x=0\)

\(\Leftrightarrow x\left(x-5\right)\left(x+5\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=5\\x=-5\end{matrix}\right.\)