Đáp án:
`b)`
`(x-1/2)(-3-x/2)=0`
`=>` \(\left[ \begin{array}{l}x-\dfrac{1}{2}=0\\-3-\dfrac{x}{2}=0\end{array} \right.\) `=>` \(\left[ \begin{array}{l}x=\dfrac{1}{2}\\\dfrac{x}{2}=-3⇒x=-6\end{array} \right.\)
`c)`
`x \ \ vdots \ \ 5 , -30<x<30`
`=> x in { -25 ; -20 ; -15 ; -10 ; .... ; 10 ; 15 ; 20 ; 25 }`