\(x\left(x-5\right)-4x+20=0\)
\(x\left(x-5\right)-4\left(x-5\right)=0\)
\(\left(x-4\right)\left(x-5\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x-4=0\\x-5=0\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=4\\x=5\end{cases}}\)
x(x-5)-4x+20=0
x(x-5)-4(x-5)=0
(x-5)(x-4)=0
=> \(\orbr{\begin{cases}x-5=0\\x-4=0\end{cases}}\)
=>\(\orbr{\begin{cases}x=5\\x=4\end{cases}}\)
Vậy ..........
#Hok tốt#^v^