\(a,\left(x+5\right)\left(x-4\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}x+5=0.\\x-4=0.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-5.\\x=4.\end{matrix}\right.\)
Vậy..........
\(b,\left(x-1\right)\left(x-3\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0.\\x-3=0.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1.\\x=3.\end{matrix}\right.\)
Vậy..........
\(c,\) Sửa đề:
\(\left(3-x\right)\left(x-3\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}3-x=0.\\x-3=0.\end{matrix}\right.\)
\(\Leftrightarrow x=3.\)
Vậy..........
\(d,x\left(x+1\right)=0.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0.\\x+1=0.\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0.\\x=-1.\end{matrix}\right.\)
Vậy..........
