a. \(\dfrac{x-1}{27}=\dfrac{-1}{3}\)
\(\Rightarrow3\left(x-1\right)=27.\left(-1\right)\)
\(3x-3=-27\)
\(3x=-27+3\)
\(3x=-24\)
\(x=-24:3\)
\(x=-8\)
b. \(\dfrac{x-3}{-25}=\dfrac{-4}{x-3}\)
\(\Rightarrow\left(x-3\right)^2=\left(-25\right).\left(-4\right)\)
\(\left(x-3\right)^2=100\)
\(\left(x-3\right)^2=10^2\)
\(\Rightarrow x-3=10\) hoặc \(x-3=-10\)
\(\Rightarrow x=10+3\) hoặc \(x=-10+3\)
\(\Rightarrow x=13\) hoặc \(x=-7\)
`a, (x-1)/27 = -1/3`
`<=> 3x - 3 = -27`
`<=> 3x = -24`
`<=> x = -8`
`b, Đk: x ne 3.`
`<=> (x-3)^2 = (-4) . (-25)`
`<=> (x-3)^2 = 100`
`<=>` \(\left[{}\begin{matrix}x-3=10\\x-3=-10\end{matrix}\right.\)
`<=>` \(\left[{}\begin{matrix}x=13\\x=-7\end{matrix}\right.\)
