\(x^2+x-12=0\\ \Leftrightarrow x^2-3x+4x-12=0\\ \Leftrightarrow\left(x-3\right)\left(x+4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=3\\x=-4\end{matrix}\right.\\ 2x^2-5x-3=0\\ \Leftrightarrow2x^2+x-6x-3=0\\ \Leftrightarrow\left(2x+1\right)\left(x-3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-\dfrac{1}{2}\\x=3\end{matrix}\right.\\ 2x^2+9x+9=0\\ \Leftrightarrow2x^2+6x+3x+9=0\\ \Leftrightarrow\left(x+3\right)\left(2x+3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-3\\x=-\dfrac{3}{2}\end{matrix}\right.\\ 6x^2-5x+1=0\\ \Leftrightarrow6x^2-2x-3x+1=0\\ \Leftrightarrow\left(3x-1\right)\left(2x-1\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=\dfrac{1}{3}\end{matrix}\right.\)
x2 + x - 12 = 0
(x - 3) (x + 4) = 0
=> x ∈ {3; -4}
2x2 - 5x - 3 = 0
(x - 3) (x + \(\dfrac{1}{2}\)) = 0
=> x ∈ {3; \(\dfrac{-1}{2}\)}
