Question

\(\dfrac{x-1}{3}=\dfrac{27}{x-1}\)

Answer 1

\(\dfrac{x-1}{3}=\dfrac{27}{x-1}\\ \Rightarrow\left(x-1\right)^2=27\cdot3\\ \Rightarrow\left(x-1\right)^2=81\\ \Rightarrow\left(x-1\right)^2=\pm8^2\\ \Rightarrow\left[{}\begin{matrix}x-1=8\\x-1=-8\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}x=9\\x=-7\end{matrix}\right.\)

Answer 2

Giúp mình với, mình cần gấp

Answer 3

Lời giải:

$\frac{x-1}{3}=\frac{27}{x-1}$

$\Rightarrow (x-1)^2=3.27=81=9^2=(-9)^2$
$\Rightarrow x-1=9$ hoặc $x-1=-9$

$\Rightarrow x=10$ hoặc $x=-8$