\(a.5x=-20\\ x=-20:5=-4\\ b.\dfrac{5}{6}-x=\dfrac{7}{4}\\ x=\dfrac{5}{6}-\dfrac{7}{4}=\dfrac{-11}{12}\)

\(5x=-20\Leftrightarrow x=-20:5\Leftrightarrow x=-4\)

\(\dfrac{5}{6}-x=\dfrac{7}{4}\Leftrightarrow x=\dfrac{5}{6}-\dfrac{7}{4}\Leftrightarrow x=-\dfrac{11}{12}\)

a,(4x-5).(5/4x-2)=0 
4x-5=0
4x=5
x=5/4

x=5/4

\(\Leftrightarrow4x-5=0\)

\(\Leftrightarrow4x=5\)

\(\Leftrightarrow x=\dfrac{5}{4}\)

Bn xem lại đề xem sao chứ chưa có kết quả chưa tìm đc x đâu nha

Ta có: \(x\left(x-4\right)+1=3x-5\)

\(\Leftrightarrow x^2-4x+1-3x+5=0\)

\(\Leftrightarrow\left(x-1\right)\left(x-6\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=6\end{matrix}\right.\)

x(x - 4) + 1 = 3x - 5

<=> x² - 4x + 1 = 3x - 5

<=> x² - 4x - 3x + 1 + 5 = 0

<=> x² - 7x + 6 = 0

<=> x² - 6x - x + 6 = 0

<=> x(x - 6) - (x - 6) = 0

<=> (x - 1)(x - 6) = 0

<=> \(\left[{}\begin{matrix}x-1=0\\x-6=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=6\end{matrix}\right.\)

x=1;2

1,2

3,6 x X = 403,2 : 14 

3,6 x X = 28,8

         X = 28,8 : 3,6

         X = 8

45,54 : x = 18 : 5

45,54 : x = 3,6

            x = 45,54 : 3,6

            x = 12.65

a) 3,6 ✖ x= 403,2 : 14            b) 45,54 :x=18:5

    3,6 ✖ x= 28,8                          45,54: x=3,6

              x=28,8: 3,6                               x=45,54:3,6

              x=8                                           x=12,65

      Vậy x=8                                           Vậy x=12,65

a) \(\dfrac{8}{x}+\dfrac{1}{5}=\dfrac{2}{5}+\dfrac{1}{3}=\dfrac{11}{15}\)

\(\dfrac{8}{x}=\dfrac{11}{15}-\dfrac{1}{5}=\dfrac{8}{15}\)

\(x=\dfrac{8\times15}{8}=15\)

B) \(\left(x-\dfrac{3}{5}\right)=\dfrac{5}{8}\times\dfrac{1}{5}=\dfrac{1}{8}\)

\(x=\dfrac{1}{8}+\dfrac{3}{5}=\dfrac{29}{40}\)

a) x² - 4 = 0

x² = 4

x = 2 hoặc x = -2

b) 2x(x + 5) - 3(5 + x) = 0

(x + 5)(2x - 3) = 0

X + 5 = 0 hoặc 2x - 3 = 0

*) x + 5 = 0

x = -5

*) 2x - 3 = 0

2x = 3

x = 3/2

c) x³ - 6x² + 11x - 6 = 0

x³ - x² - 5x² + 5x + 6x - 6 = 0

(x³ - x²) - (5x² - 5x) + (6x - 6) = 0

x²(x - 1) - 5x(x - 1) + 6(x - 1) = 0

(x - 1)(x² - 5x + 6) = 0

(x - 1)(x² - 2x - 3x + 6) = 0

(x - 1)[(x² - 2x) - (3x - 6)] = 0

(x - 1)[x(x - 2) - 3(x - 2)] = 0

(x - 1)(x - 2)(x - 3) = 0

x - 1 = 0 hoặc x - 2 = 0 hoặc x - 3 = 0

*) x - 1 = 0

x = 1

*) x - 2 = 0

x = 2

*) x - 3 = 0

x = 3

Vậy x = 1; x = 2; x = 3

\(a,x=\dfrac{1}{2}-\dfrac{2}{5}\)

\(x=\dfrac{1}{10}\)

\(b,x+\dfrac{3}{7}=\dfrac{7}{10}\)

\(x=\dfrac{7}{10}-\dfrac{3}{7}\)

\(x=\dfrac{19}{70}\)

\(c,19-x=\dfrac{17}{20}\)

\(x=19-\dfrac{17}{20}\)

\(x=\dfrac{363}{20}\)

a,1/10

b,19/70

c,18/4

x=36320

a. \(\dfrac{x}{5}=\dfrac{8}{10}\)

\(\Rightarrow10x=8.5\)

\(\Rightarrow10x=40\)

\(\Rightarrow x=\dfrac{40}{10}=4\)

b. \(\dfrac{9}{x}=\dfrac{90}{100}\)

\(\Rightarrow9.100=90x\)

\(\Rightarrow900=90x\)

\(\Rightarrow x=\dfrac{900}{90}=10\)

c. \(17+\dfrac{x}{35}=\dfrac{5}{7}\)

\(\Rightarrow\dfrac{595+x}{35}=\dfrac{25}{35}\)

\(\Rightarrow595+x=25\)

\(\Rightarrow x=25-595=-570\)

d. \(x:\dfrac{5}{27}=\dfrac{2}{9}\)

\(\Rightarrow\dfrac{27x:5}{27}=\dfrac{6}{27}\)

\(\Rightarrow27x:5=6\)

\(\Rightarrow27x=5.6\)

\(\Rightarrow27x=30\)

\(\Rightarrow x=\dfrac{30}{27}=\dfrac{10}{9}\approx1,11\)