Question

giải hệ phương trình

3x² +12=0  

Answer 1

\(\Leftrightarrow3\left(x^2+4\right)=0\)

Ta có: \(x^2+4\ge4>0\)

Vậy pt vô nghiệm

Answer 2

2x² +3x=0

Answer 3

\(\Leftrightarrow3\left(x^2+4\right)=0\)

\(\Leftrightarrow\left(x^2+4\right)=0\)

\(\Leftrightarrow\left(x-2\right)\left(x+2\right)=0\)

\(\left\{{}\begin{matrix}x-2=0\\x+2=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=2\\x=-2\end{matrix}\right.\)