a/ \(2x=0\)
\(\Leftrightarrow x=0\)
Vậy ....
b/ \(\left(x-1\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
Vậy ...
c/ \(\left(x-2\right)\left(x^2+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-2=0\\x^2+1=0\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}x=2\\x^2=-1\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=2\\x\in\varnothing\end{matrix}\right.\)
Vậy ....
d/ \(\left(x+1\right)\left(x^2-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+1=0\\x^2-4=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=-1\\x^2=4\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\\left[{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\end{matrix}\right.\)
Vậy ...
x+2=0
x = 0-2
x = -2
Vậy x = -2
(x-1).(x-2)=0
x-1=0 hoặc x-2=0
x=1 x=2
Vậy x=1 hoặc x=2
(x-2)(x^2+1)=0
x-2=0 hoặc x^2+1=0 (vô lý)
x=2 Vì x^2+1>0 với mọi số nguyên x
Vậy x=2
(x+1)(x^2-4)=0
x+1=0 hoặc x^2-4=0
x=-1 x^2=-4 (vô lý)
Vậy x=-1
