`-5x^2 +14x + 24=0`
`<=>-(5x^2-14x-24)=0`
`<=>5x^2-14x-24=0`
`<=>5x^2+6x-20x-24=0`
`<=>(5x^2+6x)-(20x+24)=0`
`<=>x(5x+6)-4(5x+6)=0`
`<=>(x-4)(5x+6)=0`
`<=>` \(\left[ \begin{array}{l}x-4=0\\5x+6=0\end{array} \right.\) `<=>` \(\left[ \begin{array}{l}x=4\\x=-\dfrac{6}{5}\end{array} \right.\)
Vậy phương trình trên có nghiệm `S={4;-6/5}`