m) \(\frac{3}{4}-x=\frac{1}{5}\)

\(x=\frac{3}{4}-\frac{1}{5}\)

\(x=\frac{11}{20}\)

Vậy \(x=\frac{11}{20}\)

o) \(\frac{3}{5}x+\frac{1}{4}=\frac{1}{10}\)

\(\frac{3}{5}x=\frac{1}{10}-\frac{1}{4}\)

\(\frac{3}{5}x=-\frac{3}{20}\)

\(x=\left(-\frac{3}{20}\right):\frac{3}{5}\)

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

Vậy \(x=-\frac{1}{4}\)

p) \(-\frac{4}{3}x+\frac{3}{2}=\frac{5}{6}\)

\(-\frac{4}{3}x=\frac{5}{6}-\frac{3}{2}\)

\(-\frac{4}{3}x=-\frac{2}{3}\)

\(x=\left(-\frac{2}{3}\right):\left(-\frac{4}{3}\right)\)

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

Vậy \(x=\frac{1}{2}\)

m) \(\frac{3}{4}\) - x = \(\frac{1}{5}\)

            x= \(\frac{3}{4}\) - \(\frac{1}{5}\)

            x= \(\frac{11}{20}\)

o) \(\frac{3}{5}\)x + \(\frac{1}{4}\) = \(\frac{1}{10}\)

            \(\frac{3}{5}\)x = \(\frac{1}{10}\) - \(\frac{1}{4}\)

            \(\frac{3}{5}\)x = -\(\frac{3}{20}\)

               x = \(\frac{-3}{20}\):\(\frac{3}{5}\)

               x = \(\frac{-1}{4}\)

p) \(\frac{-4}{3}\)x + \(\frac{3}{2}\) = \(\frac{5}{6}\)

            \(\frac{-4}{3}\)x = \(\frac{5}{6}\) - \(\frac{3}{2}\)

            \(\frac{-4}{3}\)x = \(\frac{-2}{3}\)

                 x = \(\frac{-2}{3}\) : \(\frac{-4}{3}\)

                 x = \(\frac{1}{2}\)

CHÚC BẠN HỌC TỐT

1) \(\frac{3}{4}-x=\frac{1}{5}\)<=> x=\(\frac{3}{4}-\frac{1}{5}=\frac{11}{20}\)

2) \(\frac{7}{2}+2x=-\frac{3}{4}\)<=> 2x=\(-\frac{3}{4}-\frac{7}{2}=-\frac{17}{4}\)<=> \(x=-\frac{17}{8}\)

3) \(\frac{1}{3}+\frac{2x}{3}=\frac{4}{3}\)<=> 1+2x=4<=> 2x=3<=> x=3/2

1) \(\frac{3}{4}-x=\frac{1}{5}\)

            \(x=\frac{3}{4}-\frac{1}{5}\)

            \(x=\frac{11}{20}\)

2)\(\frac{7}{2}+2x=\frac{-3}{4}\)

            \(2x=\frac{-3}{4}-\frac{7}{2}\)

            \(2x=-\frac{17}{4}\)

              \(x=-\frac{17}{4}:2\)

              \(x=-\frac{17}{8}\)

3)\(\frac{1}{3}+\frac{2}{3}x=\frac{4}{3}\)

            \(\frac{2}{3}x=\frac{4}{3}-\frac{1}{3}\)

             \(\frac{2}{3}x=1\)

                 \(x=1:\frac{2}{3}\)

                 \(x=\frac{3}{2}\)

 ^...^  ^_^

k) \(\frac{3}{4}\) - x = \(\frac{1}{5}\)

           x = \(\frac{3}{4}\) - \(\frac{1}{5}\)

           x = \(\frac{11}{20}\)

l) \(\frac{7}{2}\) + 2.x = \(\frac{-3}{4}\)

   \(\frac{7}{2}\) + 2x = \(\frac{-3}{4}\)

          2x = \(\frac{-3}{4}\) -\(\frac{7}{2}\)

          2x = \(\frac{-17}{4}\)

            x = \(\frac{-17}{4}\) : 2

            x = \(\frac{-17}{8}\)

m) Lặp lại câu k

n) \(\frac{1}{3}\) + \(\frac{2}{3}\).x = \(\frac{4}{3}\)

     \(\frac{1}{3}\) + \(\frac{2}{3}\)x = \(\frac{4}{3}\)

            \(\frac{2}{3}\)x = \(\frac{4}{3}\) - \(\frac{1}{3}\)

            \(\frac{2}{3}\)x = 1

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

               x = \(\frac{3}{2}\)

CHÚC BẠN HỌC TỐT

g) Đặt k = \(\frac{x-1}{2}\) = \(\frac{y-2}{3}\) = \(\frac{z-3}{4}\)

=> \(\begin{cases}x-1=2k\\y-2=3k\\z-3=4k\end{cases}\)

=> \(\begin{cases}x=2k+1\\y=3k+2\\z=4k+3\end{cases}\)

=> x - 2y + 3z = 2k+1 - 6k - 4 + 12k + 9 = 8k + 6

=> 8k + 6 = 14

=> k = 1

=> \(\begin{cases}x=2\\y=5\\z=7\end{cases}\)

Nguyễn Huy Thắng Hoàng Lê Bảo Ngọc giúp câu h với 

\(\frac{12x-15y}{7}=\frac{20z-12x}{9}=\frac{15y-20z}{11}=\frac{12x-15y+20z-12x+15y-20z}{7+9+11}=0\)

\(\left[\begin{array}{nghiempt}12x-15y=0\\20z-12x=0\\15y-20z=0\end{array}\right.\)

\(\left[\begin{array}{nghiempt}12x=15y\\20z=12x\\15y=20z\end{array}\right.\)

\(\left[\begin{array}{nghiempt}\frac{x}{15}=\frac{y}{12}\\\frac{z}{12}=\frac{x}{20}\\\frac{y}{20}=\frac{z}{15}\end{array}\right.\)

mk sắp phải đi học rồi các bạn giúp mình với có đc ko mk nhớ sẽ đền đáp công ơn của bạn 

a) (5 - x) +12 = -25

<-> 5 - x + 12 = -25

<-> 17 - x = - 25

<-> x = 42

b) 12 - 4(x - 2) = -4

<-> 12 - 4x + 8 = -4

<-> 20 - 4x = -4

<-> 4x = 24

<-> x = 6

a) (5 - x) + 12 = -25

<=> -x = -25 - 12 - 5

<=> -x = -42

<=> x = 42

b) 12 - 4(x - 2) = -4

<=> 12 - 4x + 8 = -4

<=> -4x = -4 - 8 - 12

<=> -4x = -24

<=> x = 6

c) -15 - |3 - x| = -19

<=> -|3 - x| = -4

<=> 3 - x = 4 hoặc 3 - x = -4

<=> x = -1 hoặc x = 7

Bài 1:

a) Ta có: \(\frac{-5}{8}+x=\frac{4}{9}\)

\(\Leftrightarrow x=\frac{4}{9}-\frac{-5}{8}=\frac{32}{72}-\frac{-45}{72}\)

hay \(x=\frac{77}{72}\)

Vậy: \(x=\frac{77}{72}\)

b) Ta có: \(1\frac{3}{4}\cdot x+1\frac{1}{2}=-\frac{4}{5}\)

\(\Leftrightarrow\frac{7}{4}\cdot x+\frac{3}{2}=-\frac{4}{5}\)

\(\Leftrightarrow\frac{7}{4}\cdot x=-\frac{4}{5}-\frac{3}{2}=-\frac{23}{10}\)

\(\Leftrightarrow x=\frac{-23}{10}:\frac{7}{4}=\frac{-23}{10}\cdot\frac{4}{7}\)

hay \(x=-\frac{46}{35}\)

Vậy: \(x=-\frac{46}{35}\)

c) Ta có: \(\frac{1}{4}+\frac{3}{4}x=\frac{3}{4}\)

\(\Leftrightarrow\frac{3}{4}x=\frac{2}{4}\)

\(\Leftrightarrow x=\frac{2}{4}:\frac{3}{4}=\frac{2}{4}\cdot\frac{4}{3}\)

hay \(x=\frac{2}{3}\)

Vậy: \(x=\frac{2}{3}\)

d) Ta có: \(x\cdot\left(\frac{1}{4}+\frac{1}{5}\right)-\left(\frac{1}{7}+\frac{1}{8}\right)=0\)

\(\Leftrightarrow x\cdot\frac{9}{20}-\frac{15}{56}=0\)

\(\Leftrightarrow x\cdot\frac{9}{20}=\frac{15}{56}\)

\(\Leftrightarrow x=\frac{15}{56}:\frac{9}{20}=\frac{15}{56}\cdot\frac{20}{9}\)

hay \(x=\frac{25}{42}\)

Vậy: \(x=\frac{25}{42}\)

e) Ta có: \(\frac{3}{35}-\left(\frac{3}{5}+x\right)=\frac{2}{7}\)

\(\Leftrightarrow\frac{3}{35}-\frac{3}{5}-x=\frac{2}{7}\)

\(\Leftrightarrow\frac{-18}{35}-x=\frac{2}{7}\)

\(\Leftrightarrow-x=\frac{2}{7}-\frac{-18}{35}=\frac{2}{7}+\frac{18}{35}=\frac{4}{5}\)

hay \(x=-\frac{4}{5}\)

Vậy: \(x=-\frac{4}{5}\)

f) Ta có: \(\frac{3}{7}+\frac{1}{7}:x=\frac{3}{14}\)

\(\Leftrightarrow\frac{1}{7}\cdot\frac{1}{x}=\frac{3}{14}-\frac{3}{7}=\frac{-3}{14}\)

\(\Leftrightarrow\frac{1}{x}=\frac{-3}{14}:\frac{1}{7}=-\frac{3}{14}\cdot7=-\frac{3}{2}\)

\(\Leftrightarrow x=\frac{1\cdot2}{-3}=\frac{2}{-3}=-\frac{2}{3}\)

Vậy: \(x=-\frac{2}{3}\)

g) Ta có: \(\left(5x-1\right)\left(2x-\frac{1}{3}\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}5x-1=0\\2x-\frac{1}{3}=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}5x=1\\2x=\frac{1}{3}\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{5}\\x=\frac{1}{3}:2=\frac{1}{6}\end{matrix}\right.\)

Vậy: \(x\in\left\{\frac{1}{5};\frac{1}{6}\right\}\)

a) \(\dfrac{-1}{5}< \dfrac{1}{x}< \dfrac{1}{7}\)

\(\Leftrightarrow\dfrac{1}{-5}< \dfrac{1}{x}< \dfrac{1}{7}\)

\(\Rightarrow\) \(x< -5\) và \(x< 7\left(x\in Z\right)\)

b) \(\dfrac{14}{5}< \dfrac{x}{5}< 4\)

\(\Leftrightarrow\dfrac{14}{5}< \dfrac{x}{5}< \dfrac{20}{5}\)

\(\Rightarrow14< x< 20\) mà \(x\in Z\)

\(\Rightarrow x\in\left\{15;16;17;18;19\right\}\)

c) \(\dfrac{1}{3}< \dfrac{9}{x}< \dfrac{1}{2}\)

\(\Leftrightarrow\dfrac{9}{27}< \dfrac{9}{x}< \dfrac{9}{18}\)

\(\Rightarrow18< x< 27\) mà \(x\in Z\)

\(\Rightarrow x\in\left\{19;20;...;25;26\right\}\)