Question

Tìm x:

\(\frac{x-3}{3}=\frac{27}{x-3}\)

Answer 1

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

⇔\(\frac{\left(x-3\right)\left(x-3\right)}{3\left(x-3\right)}-\frac{81}{3\left(x-3\right)}=0\)

\(\Rightarrow\left(x-3\right)^2-81=0\)

\(\Leftrightarrow x^2-6x+9-81=0\)

\(\Leftrightarrow x^2-6x-72=0\)

⇔ x \(^2\) - 12x + 6x - 72 = 0

⇔ x( x - 12 ) + 6 ( x - 12 ) =0

⇔ ( x + 6 ) ( x - 12 ) = 0

\(\Leftrightarrow\left[{}\begin{matrix}x+6=0\\x-12=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-6\\x=12\end{matrix}\right.\)

Answer 2

x-3/3=27/x-3

=>(x-3)(x-3)/3.(x-3)=27.3/3.(x-3)

=>(x-3)²=81

=>(x-3)²=9²

^=>x-3=9

^=>x=12

Vay x=12.

chuc hk tot.