a, \(\dfrac{x}{2}=\dfrac{2}{4}\Rightarrow2x=2\Leftrightarrow x=1\)
b, \(\dfrac{x}{6}=-\dfrac{1}{3}\Rightarrow x=-2\)
c, \(-\dfrac{1}{5}=\dfrac{2}{x}\Rightarrow x=-10\)
d, \(\dfrac{8}{3}=-\dfrac{12}{x}\Rightarrow\dfrac{24}{9}=-\dfrac{24}{2x}\Rightarrow-2x=9\Leftrightarrow x=-\dfrac{9}{2}\)
e, \(\dfrac{x}{5}=\dfrac{5}{x}\Rightarrow x^2=25\Leftrightarrow x=\pm5\)
f, \(\dfrac{x}{-6}=-\dfrac{6}{x}\Rightarrow x^2=36\Leftrightarrow x=\pm6\)
Bài 8:
a) \(\dfrac{3}{4}=\dfrac{x}{x+1}\)
\(\Rightarrow3x+3=4x\)
\(\Rightarrow x=3\)
Vậy: \(x=3\)
b) \(\dfrac{2}{3}=\dfrac{x+1}{2x}\)
\(\Rightarrow4x=3x+3\)
\(\Rightarrow x=3\)
Vậy: \(x=3\)
c) \(\dfrac{1}{x+1}=\dfrac{2}{x+3}\)
\(\Rightarrow x+3=2x+2\)
\(\Rightarrow x=1\)
Vậy: \(x=1\)
d) \(\dfrac{5}{4x-2}=-\dfrac{1}{5-x}\)
\(\Rightarrow25-5x=-4x+2\)
\(\Rightarrow x=23\)
Vậy: \(x=23\)
Bài 7:
a: =>x+2=2
hay x=0
b: \(\Leftrightarrow x-1=-2\)
hay x=-1
c: \(\Leftrightarrow10x=-20\)
hay x=-2
d: \(\Leftrightarrow9-x=-20\)
hay x=29
e: \(\Leftrightarrow\left(x+2\right)^2=9\)
\(\Leftrightarrow\left[{}\begin{matrix}x+2=3\\x+2=-3\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=1\\x=-5\end{matrix}\right.\)
f: \(\Leftrightarrow\left(x-4\right)^2=25\)
=>x-4=5 hoặc x-4=-5
=>x=9 hoặc x=-1
