$g(x)=(2x-1)(6x+1)(12x+1)(20x+1)(30x+1)$
Để $g(x)=0$ thì
$\left[\begin{matrix}2x-1=0\\6x+1=0\\12x+1=0\\20x+1=0\\30x+1=0\end{matrix}\right.$
$\Leftrightarrow \left[\begin{matrix}x=\dfrac{1}{2}\\x=\dfrac{-1}{6}\\x=\dfrac{-1}{12}\\x=\dfrac{-1}{20}\\x=\dfrac{-1}{30}\end{matrix}\right.$
Vậy $g(x)$ có tập nghiệm
$S=\bigg\{\dfrac{1}{2};\dfrac{-1}{6};\dfrac{-1}{12};\dfrac{-1}{20};\dfrac{-1}{30}\bigg\}$
Tổng các nghiệm
$\dfrac{1}{2}+\dfrac{-1}{6}+\dfrac{-1}{12}+\dfrac{-1}{20}+\dfrac{-1}{30}\\=\dfrac{30}{60}-\dfrac{10}{60}-\dfrac{5}{60}-\dfrac{3}{60}-\dfrac{2}{60}\\=\dfrac{10}{60}=\dfrac{1}{6}$
