Từ \(\dfrac{x}{9}=\dfrac{1}{x}\Rightarrow x\cdot x=1\cdot9\\ x^2=9=\left(\pm3\right)^2\\ \Rightarrow\left\{{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)

170 (nha)

Ai k mình mình k lại

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

\(\Rightarrow\left(x-2\right)^2=\left(\pm1\right)^2\)

\(\Rightarrow\left\{{}\begin{matrix}x-2=1\\x-2=-1\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=1+2\\x=-1+2\end{matrix}\right.\)

\(\Rightarrow\left\{{}\begin{matrix}x=3\\x=1\end{matrix}\right.\)

phải bạn ạ

a) =>\(\left\{{}\begin{matrix}2x-4=3x+5\\2x-4=-3x-5\end{matrix}\right.\)

Với 2x - 4 = 3x + 5 Với 2x - 4 = -3x - 5

=>2x - 3x = 5 + 4 =>2x + 3x = -5 + 4

-1x = 9 5x = -1

x = 9 : (-1) x = \(\dfrac{-1}{5}\)

x = -9