`x ²+3x-10=0 `
`(x ²-2x)+(5x-10)=0 `
`x(x-2)+5(x-2)=0 `
`(x-2)(x+5)=0 `
\(\left[ \begin{array}{l}x-2=0\\x+5=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=2\\x=-5\end{array} \right.\)
`x(x-1)=12`
`x^2-x-12=0`
`(x^2-4x)+(3x-12)=0`
`x(x-4)+3(x-4)=0`
`(x-4)(x+3)=0`
\(\left[ \begin{array}{l}x-4=0\\x+3=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=4\\x=-3\end{array} \right.\)