\(\dfrac{x-1}{-15}=\dfrac{60}{1-x}\\ \dfrac{1-x}{15}=\dfrac{60}{1-x}\\ \left(1-x\right)^2=60.5\\ \left(1-x\right)^2=900\\ \left[{}\begin{matrix}1-x=30\\1-x=-30\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-29\\x=31\end{matrix}\right.\)
Vậy..
(x-1).(x-1)=-15.60
=>(x-1)^2=-900
=>(x-1)^2=30^2
=>x-1=30
=>x=31
\(\dfrac{x-1}{-15}=\dfrac{60}{1-x}\Leftrightarrow\dfrac{1-x}{15}=\dfrac{60}{1-x}\)( đk x khác 1)
\(\Leftrightarrow\left(1-x\right)^2=15.60=30^2\)
\(\Leftrightarrow\left|1-x\right|=30\)
\(\Leftrightarrow\left[{}\begin{matrix}1-x=30\\1-x=-30\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-29\\x=31\end{matrix}\right.\)
