Question

Tìm x

(x-5)(3-2x)+3x-15=0

Answer 1

\(\left(x-5\right)\left(3-2x\right)+3x-15=0\\ \left(x-5\right)\left(3-2x\right)+3\left(x-5\right)=0\\ \left(x-5\right)\left(3-2x+3\right)=0\\ \left(x-5\right)\left(6-2x\right)=0\\ \left[{}\begin{matrix}x-5=0\\6-2x=0\end{matrix}\right.\\ \left[{}\begin{matrix}x=0+5\\-2x=0-6\end{matrix}\right.\\ \left[{}\begin{matrix}x=5\\-2x=-6\end{matrix}\right.\\ \left[{}\begin{matrix}x=5\\x=6-:\left(-2\right)\end{matrix}\right.\\ \left[{}\begin{matrix}x=5\\x=3\end{matrix}\right.\)

Answer 2

\(( x − 5 ) ( 3 − 2 x ) + 3 x − 15 = 0\)

\(⇒ ( x − 5 ) . ( 3 − 2 x ) + 3 . ( x − 5 ) = 0\)

\(⇒ ( x − 5 ) . ( 3 − 2 x + 3 ) = 0\)

\(⇒ ( x − 5 ) . ( 6 − 2 x ) = 0\)

\(\Rightarrow\left[{}\begin{matrix}x-5=0\\6-2x=0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\-2x=-0\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=5\\x=3\end{matrix}\right.\)

Vậy `x in {5;3}`

Answer 3