x^2+3x+x+3=0
x(x+3)+(x+3)=0
(x+1)(x+3)=0
=> x+1=0 hoặc x+3=0
=> x= -1 hoặc x-3
\(x^2+4x+3=0\)
=>\(x^2+x+3x+3=0\)
=>\(x\left(x+1\right)+3\left(x+1\right)=0\)
=>\(\left(x+1\right)\left(x+3\right)=0\)
=>\(\orbr{\begin{cases}x+1=0\\x+3=0\end{cases}\Rightarrow\orbr{\begin{cases}x=-1\\x=-3\end{cases}}}\)
\(x^2+4x+3=0\)
\(\Rightarrow x^2+x+3x+3=0\)
\(\Rightarrow x\left(x+1\right)+3\left(x+1\right)=0\)
\(\Rightarrow\left(x+1\right)\left(x+3\right)=0\)
\(\Rightarrow\orbr{\begin{cases}x+1=0\Rightarrow x=-1\\x+3=0\Rightarrow x=-3\end{cases}}\)
vậy.....
k mk nha ^-^
x^2+4x+3=0
x^2+1x+3x+3=0
x(x+1)+3(x+1)=0
(x+3)(x+1)=0
x+3=0 hoặc x+1=0
x=-3 x=-1
