\(a,\left(x-2\right)\left(3x-9\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-2=0\\3x-9=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\\3x=9\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=2\\x=3\end{matrix}\right.\)
\(b,\left(3-x\right)\left(x+5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}3-x=0\\x+5=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=3\\x=-5\end{matrix}\right.\)
\(c,\left(x+1\right)\left(4-2x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\4-2x=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-1\\2x=4\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=-1\\x=2\end{matrix}\right.\)
a)(x-2 ).(3x-9)=0
x-2 =0
x=0+2
x=2
Hoặc :3x-9 =0
3x =0+9
3x =9
x =9\(\div\)3
x =3
Vậy : x bằng 2 hoặc bằng 3
b)(3-x).(x+5)=0
3-x =0
x =3-0
x =3
Hoặc : x+5 =0
x =0-5
x =-5
Vậy x bằng 3 hoặc bằng -5
c)(x+1).(4-2x)=0
x+1 =0-1
=-1
Hoặc : 4-2x =0
2x =4-0
2x =4
x =4\(\div\)2
x =2
Vậy x bằng -1 hoặc 2
