a, \(x^2+10x=0\)
\(\Leftrightarrow x\left(x+10\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x+10=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=0\\x=-10\end{matrix}\right.\)
Vậy x = 0 hoặc x = -10
b, \(\left(x-7\right)^3=\left(x-7\right)\)
\(\Leftrightarrow\left(x-7\right)^3-\left(x-7\right)=0\)
\(\Leftrightarrow\left(x-7\right)\left[\left(x-7\right)^2-1\right]=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-7=0\\\left(x-7\right)^2-1=0\end{matrix}\right.\)
+) \(x-7=0\Leftrightarrow x=7\)
+) \(\left(x-7\right)^2-1=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-7=1\\x-7=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=8\\x=6\end{matrix}\right.\)
Vậy x = 7 hoặc x = 8 hoặc x = 6
c, \(x^2-20x+100=0\)
\(\Leftrightarrow\left(x-10\right)^2=0\)
\(\Leftrightarrow x=10\)
Vậy x = 10
