=3/7*4/4+3/7*3/2 

= 3/7*(4/4+3/2)

........... 

\(\frac{3}{4}\times\frac{4}{7}+\frac{3}{7}\times\frac{3}{2}\)

\(=\frac{3}{7}+\frac{9}{14}=\frac{15}{14}\)

\(X+\frac{31}{2}+X=24\frac{1}{4}\)

\(\Rightarrow2x+\frac{31}{2}=24\frac{1}{4}\)

\(\Rightarrow2x=24\frac{1}{4}-\frac{31}{2}\)

\(\Rightarrow2x=\frac{35}{4}\)

\(\Rightarrow x=\frac{35}{4}:2=\frac{35}{8}\)

Ta có: \(A=\dfrac{-5}{7}:\left(25-24\dfrac{4}{7}\right)+15\dfrac{1}{3}\cdot\dfrac{-1}{23}\)

\(=\dfrac{-5}{7}:\left(25-\dfrac{172}{7}\right)+\dfrac{46}{5}\cdot\dfrac{-1}{23}\)

\(=\dfrac{-5}{7}\cdot\dfrac{7}{3}+\dfrac{-2}{5}\)

\(=\dfrac{-5}{3}+\dfrac{-2}{5}\)

\(=\dfrac{-31}{15}\)

c) tách ra  4/x-6=-12/18 và y/24=-12/18 rồi giải x, y

d) tách ra -1/5 <= x/8 và x/8 <= 1/4 rồi giải ra x

f) y và y/5 = 6y/5 rồi giải ra tìm y

\(\text{a) }\frac{-4}{x-1}=\frac{x-1}{-9}\)

\(\Leftrightarrow\left(x-1\right).\left(x-1\right)=\left(-4\right).\left(-9\right)\)

\(\Leftrightarrow\left(x-1\right)^2=36\)

\(\Leftrightarrow x-1=\sqrt{36}\)

\(\Leftrightarrow x-1=6\)

\(\Leftrightarrow x=7\)

\(a,\frac{-4}{x-1}=\frac{x-1}{-9}\)

\(\Rightarrow(x-1)(x-1)=(-4)\cdot(-9)\)

\(\Rightarrow(x-1)^2=36\)

\(\Rightarrow(x-1)^2=6^2\)

\(\Rightarrow x-1=\pm6\)

\(\Rightarrow\hept{\begin{cases}x-1=6\\x-1=-6\end{cases}}\Rightarrow\hept{\begin{cases}x=7\\x=-5\end{cases}}\)

\(b,-1,75\cdot x+3\frac{3}{4}=-24\)

\(\Rightarrow-1,75\cdot x+3,75=-24\)

\(\Rightarrow-1,75\cdot x=-24-3,75\)

\(\Rightarrow-1,75\cdot x=-27,75\)

\(\Rightarrow x=-27,75:(-1,75)\)

 Tính rồi tìm ra giá trị của x thôi :v

a) -4/x-1=x-1/-9

<=> (x-1).(x-1)=-4.-9

<=> (x-1)² = 36

<=> (x-1)² = (\(\pm\)6²)

<=>\(\orbr{\begin{cases}x-1=6\\x-1=-6\end{cases}}\)

<=>\(\orbr{\begin{cases}x=6+1=7\\x=-6+1=5\end{cases}}\)

Vậy x \(\in\){7,5}

a) \(x+1,23\div3=1,845\)                                                       c) Không rõ 

\(x+0,41=1,845\)

\(x=1,845-0,41\)

\(x=1,435\)

b) \(x\times\frac{1}{4}+x\times\frac{1}{5}+x\times2=19,6\)                                 d) \(x+3\frac{1}{2}+20=24\frac{1}{4}\)

\(x\times\left(\frac{1}{4}+\frac{1}{5}+2\right)=19,6\)                                                  \(x+\frac{7}{2}+20=\frac{97}{4}\)

\(x\times\frac{49}{20}=19,6\)                                                                          \(x+\frac{47}{2}=\frac{97}{4}\)

\(x=19,6\div\frac{49}{20}\)                                                                          \(x=\frac{97}{4}\div\frac{47}{2}\) 

\(x=8\)                                                                                               \(x=\frac{97}{94}\)

x + 1.23 = 5.535

x = 4.305

X + 1,23 : 3 = 1,845

X + 0,41      = 1,845

      X          = 1,845 - 0,41

                  = 1,435

X x 1/4 + X x 1/5 + X x 2 = 19,6

X x ( 1/4 + 1/5 + 2 )         = 19,6

X x  2,45                         = 19,6

       X                             =  19, 6 : 2, 45

       X                             =   8

Hoctot

a: Ta có: \(100-7\left(x-5\right)=58\)

\(\Leftrightarrow7\left(x-5\right)=42\)

\(\Leftrightarrow x-5=6\)

hay x=11

b: Ta có: \(12\left(x-1\right):3=4^3+2^3\)

\(\Leftrightarrow12\left(x-1\right)=216\)

\(\Leftrightarrow x-1=18\)

hay x=19

`Answer:`

a. \(\frac{17}{2}-\left|2x-\frac{3}{4}\right|=-\frac{7}{4}\)

\(\Leftrightarrow\left|2x-\frac{3}{4}\right|=\frac{17}{2}+\frac{7}{4}\)

\(\Leftrightarrow\left|2x-\frac{3}{4}\right|=\frac{41}{4}\)

\(\Leftrightarrow\orbr{\begin{cases}2x-\frac{3}{4}=\frac{41}{4}\\2x-\frac{3}{4}=-\frac{41}{4}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}2x=\frac{41}{4}+\frac{3}{4}\\2x=-\frac{41}{4}+\frac{3}{4}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}2x=11\\2x=-\frac{19}{2}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=11:2\\x=-\frac{19}{2}:2\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{11}{2}\\x=-\frac{19}{4}\end{cases}}\)

b. \(\left(x+\frac{1}{5}\right)^2+\frac{17}{25}=\frac{26}{25}\)

\(\Leftrightarrow\left(x+\frac{1}{5}\right)^2=\frac{26}{25}-\frac{17}{25}\)

\(\Leftrightarrow\left(x+\frac{1}{5}\right)^2=\frac{9}{25}\)

\(\Leftrightarrow\left(x+\frac{1}{5}\right)=\left(\frac{3}{5}\right)^2\)

\(\Leftrightarrow\orbr{\begin{cases}x+\frac{1}{5}=\frac{3}{5}\\x+\frac{1}{5}=-\frac{3}{5}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{3}{5}-\frac{1}{5}\\x=-\frac{3}{5}-\frac{1}{5}\end{cases}}\)

\(\Leftrightarrow\orbr{\begin{cases}x=\frac{2}{5}\\x=-\frac{4}{5}\end{cases}}\)

c. \(-1\frac{5}{27}-\left(3x-\frac{7}{9}\right)^3=-\frac{24}{27}\)

\(\Leftrightarrow-\frac{32}{27}-\left(3x-\frac{7}{9}\right)^3=-\frac{24}{27}\)

\(\Leftrightarrow\left(3x-\frac{7}{9}\right)^3=-\frac{32}{27}-\left(-\frac{24}{27}\right)\)

\(\Leftrightarrow\left(3x-\frac{7}{9}\right)^3=-\frac{8}{27}\)

\(\Leftrightarrow\left(3x-\frac{7}{9}\right)^3=\left(-\frac{2}{3}\right)^3\)

\(\Leftrightarrow3x-\frac{7}{9}=-\frac{2}{3}\)

\(\Leftrightarrow3x=-\frac{2}{3}+\frac{7}{9}\)

\(\Leftrightarrow3x=\frac{1}{9}\)

\(\Leftrightarrow x=\frac{1}{9}:3\)

\(\Leftrightarrow x=\frac{1}{27}\)