Question

\(\dfrac{x-3}{-3}\)=\(\dfrac{-12}{x-3}\)

Answer 1

\(ĐK:x\ne3\)

\(\Rightarrow\left(x-3\right)\left(x-3\right)=-12.-3\)

\(\Leftrightarrow\left(x-3\right)^2=36\)

\(\Leftrightarrow\left(x-3\right)^2=6^2\)

\(\Leftrightarrow\left[{}\begin{matrix}x-3=6\\x-3=-6\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-3\end{matrix}\right.\)

Answer 2

đk : x khác 3 

\(\left(x-3\right)^2=36\Leftrightarrow\left[{}\begin{matrix}x-3=6\\x-3=-6\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=9\\x=-3\end{matrix}\right.\)(tm) 

Answer 3

\(\dfrac{\left(x-3\right).\left(x-3\right)}{-3.\left(x-3\right)}=\dfrac{-12.-3}{\left(x-3\right).-3}\)

=>(x-3)²=36

=>(x-3)²=6²

=>x=+-9

Answer 4

\(\dfrac{x-3}{-3}=\dfrac{-12}{x-3}\)

\(\Leftrightarrow\left(x-3\right)\cdot\left(x-3\right)=\left(-12\right)\cdot\left(-3\right)\)

\(\Leftrightarrow x^2-6x+9=36\)

\(\Leftrightarrow x^2-6x+9-36=36\)

\(\Leftrightarrow x^2-6x+9-36=36-36\)

\(\Leftrightarrow x^2-6x-27=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x-9=0\end{matrix}\right.\) \(\Leftrightarrow x=\left[{}\begin{matrix}-3\\9\end{matrix}\right.\)