a,\(5+3x-\left(2+x\right)< 5x+1\)
\(\Rightarrow5+3x-2-x-5x-1< 0\)
\(\Rightarrow-3x< -5+2+1\Rightarrow x< \dfrac{2}{3}\)
b, \(\left(x-2\right)\left(x+1\right)-x\left(x+4\right)\le x\)
\(\Rightarrow x^2+x-2x-2-\left(x^2+4x\right)-x\le0\)
\(\Rightarrow x^2-x-2-x^2-4x-x\le0\)
\(\Rightarrow-6x\le2\Rightarrow x\le-\dfrac{1}{3}\)
Chúc bạn học tốt!!!