\(a,\left(x-1\right)\left(x+2\right)\le0\)
th1 :
\(\hept{\begin{cases}x-1\ge0\\x+2\le0\end{cases}\Rightarrow\hept{\begin{cases}x\ge1\\x\le-2\end{cases}}\Rightarrow loai}\)
th2 :
\(\hept{\begin{cases}x-1\le0\\x+2\ge0\end{cases}\Rightarrow\hept{\begin{cases}x\le1\\x\ge-2\end{cases}\Rightarrow}-2\le x\le1}\)
\(b,\left(x-5\right)\left(3-x\right)>0\)
th1 :
\(\hept{\begin{cases}x-5>0\\3-x>0\end{cases}\Rightarrow\hept{\begin{cases}x>5\\x< 3\end{cases}\Rightarrow}loai}\)
th2 :
\(\hept{\begin{cases}x-5< 0\\3-x< 0\end{cases}\Rightarrow\hept{\begin{cases}x< 5\\x>3\end{cases}\Rightarrow}3< x< 5}\)
c tương tự nha em
