\(4-\left(7-x\right)=x-\left(13-4\right)\)

\(4-7+x=x-13+4\)

\(x-x=-13+4-4+7\)

\(0x=-6\)(Vô lí)

Vậy không có giá trị x thỏa biểu thức

Bài làm

4 - ( 7 - x ) = x - ( 13 - 4 )

4 - 7 + x = x - 13 + 4

x - x = 7 - 4 - 13 + 4

x( 1 - 1 ) = -6

x . 0 = -6

0 = -6 ( Vô lí )

Vậy \(x\in\varnothing\)

# Học tốt #

\(4-\left(7-x\right)=x-\left(13-4\right)\)

\(4-7+x=x-9\)

\(x-x=-9-4+7\)

\(0x=-6\)

\(\Rightarrow x\)vô nghiệm 

hay \(x\in\varnothing\)

vậy \(x\in\varnothing\)

\(|x-4|-13\)

\(\Leftrightarrow \left[\begin{array}{} x-4=13\\ x-4=-13 \end{array} \right.\)

\(\Leftrightarrow \left[\begin{array}{} x=13+4\\ x=(-13)+4 \end{array} \right.\)

\(\Leftrightarrow \left[\begin{array}{} x=17\\ x=-9 \end{array} \right.\)

 Vậy x ∈ {17;-9}

\(|x-4|-13=7\)

\(\Leftrightarrow |x-4|=7+13\)

\( \Leftrightarrow |x-4|=20\)

\(\Leftrightarrow \left[\begin{array}{} x-4=20\\ (x-4=-20 \end{array} \right.\)

\(\Leftrightarrow \left[\begin{array}{} x=20+4\\ x=(-20)+4 \end{array} \right.\)

\(\Leftrightarrow \left[\begin{array}{} x=24\\ x=-16 \end{array} \right.\)

Vậy x ∈{24;-16}

\(\left|\left|x-4\right|-13\right|=7\)

\(\Leftrightarrow\left[{}\begin{matrix}\left|x-4\right|-13=7\\\left|x-4\right|-13=-7\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}\left|x-4\right|=21\\\left|x-4\right|=6\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x-4=21\\x-4=-21\end{matrix}\right.\\\left[{}\begin{matrix}x-4=6\\x-4=-6\end{matrix}\right.\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}\left[{}\begin{matrix}x=25\\x=-17\end{matrix}\right.\\\left[{}\begin{matrix}x=10\\x=-2\end{matrix}\right.\end{matrix}\right.\)

con bà mày

quá ghê gớm

4 - ( 7 - x ) = x - ( 13 - 4 )

4 - ( 7 - x ) = x - 9

7 - x = x - 9 - 4 = x - 13

7 - x = x - 13

=> x = 10

4 - ( 7 - x ) = x - 9

4 - 7 + x    = x - 9

-3     + x   = x - 9

-3  + 9     = 2x

6             = 2x

3             = x

Vậy x = 3

\(a,\dfrac{2}{3}.x=\dfrac{2}{7}\\ x=\dfrac{2}{7}:\dfrac{2}{3}=\dfrac{3}{7}\\ ---\\ b,x.\dfrac{3}{5}=\dfrac{2}{5}\\ x=\dfrac{2}{5}:\dfrac{3}{5}=\dfrac{2}{3}\\ ---\\ c,x:\dfrac{8}{13}=\dfrac{13}{7}\\x=\dfrac{13}{7}.\dfrac{8}{13}=\dfrac{8}{7}\\ ----\\ d,\dfrac{3}{2}:x=\dfrac{7}{4}\\ x=\dfrac{3}{2}:\dfrac{7}{4}=\dfrac{3}{2}.\dfrac{4}{7}=\dfrac{6}{7}\)