a) Ta có: \(x\left(x+3\right)-2x-6=0\)
\(\Leftrightarrow x\left(x+3\right)-\left(2x+6\right)=0\)
\(\Leftrightarrow x\left(x+3\right)-2\left(x+3\right)=0\)
\(\Leftrightarrow\left(x+3\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x+3=0\\x-2=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-3\\x=2\end{matrix}\right.\)
Vậy: \(x\in\left\{-3;2\right\}\)
b) Ta có: \(4x^2-1+x\left(2x-1\right)=0\)
\(\Rightarrow\left(2x\right)^2-1^2+x\left(2x-1\right)=0\)
\(\Rightarrow\left[\left(2x\right)^2-1^2\right]+x\left(2x-1\right)=0\)
\(\Rightarrow\left(2x-1\right)\left(2x+1\right)+x\left(2x-1\right)=0\)
\(\Leftrightarrow\left(2x-1\right)\left(2x+1+x\right)=0\)
\(\Rightarrow\left(2x-1\right)\left(3x+1\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\3x+1=0\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}2x=1\\3x=-1\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\frac{1}{2}\\x=\frac{-1}{3}\end{matrix}\right.\)
Vậy: \(x\in\left\{\frac{1}{2};\frac{-1}{3}\right\}\)
a, x(x+3)-2x-6=0
⇔x(x+3)-2(x+3)=0
⇔(x+3)(x-2)=0
⇔x+3=0 hoặc x-2=0
⇔x= -3 hoặc x=2
b, 4x2-1+x(2x-1)=0
⇔(2x-1)(2x+1)+x(2x-1)=0
⇔(2x-1)(2x+1+x)=0
⇔(2x-1)(3x+1)=0
⇔2x-1=0 hoặc 3x+1=0
⇔x=1/2 hoặc x= -1/3