d.=>\(\left\{{}\begin{matrix}x-1=0\\x^2-4=0\end{matrix}\right.\)=>\(\left\{{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)
Vậy x ∈ {1; 2}
e. x.x2 + 3x = 0
x(x2 + 3) = 0
=>\(\left\{{}\begin{matrix}x=0\\x^2+3=0\end{matrix}\right.\)=>\(\left\{{}\begin{matrix}x=0\\x=\sqrt[2]{3}\end{matrix}\right.\)
Vậy x ∈ { 0; \(\sqrt[2]{3}\)}
câu f cậu làm tương tự nhé