\(f\left(x\right)=\dfrac{3}{2x-1}-\dfrac{1}{x+2}=\dfrac{3\left(x+2\right)-\left(2x-1\right)}{\left(2x-1\right)\left(x+2\right)}\) \(=\dfrac{x+7}{\left(2x-1\right)\left(x+2\right)}\). \(x+7=0\Leftrightarrow x=-7\); \(2x-1=0\Leftrightarrow x=\dfrac{1}{2}\); \(x+2=0\Leftrightarrow x=-2\). TenAnh1 TenAnh1 B = (11.24, -6.26) B = (11.24, -6.26) B = (11.24, -6.26) C = (-0.38, -6.9) C = (-0.38, -6.9) C = (-0.38, -6.9) D = (14.98, -6.9) D = (14.98, -6.9) D = (14.98, -6.9) E = (-0.4, -6.68) E = (-0.4, -6.68) E = (-0.4, -6.68) F = (13.84, -6.58) F = (13.84, -6.58) F = (13.84, -6.58) G = (-0.44, -6.72) G = (-0.44, -6.72) G = (-0.44, -6.72) H = (14.92, -6.72) H = (14.92, -6.72) H = (14.92, -6.72) Vậy \(f\left(x\right)=0\) khi \(x=\left\{-7\right\}\). \(f\left(x\right)>0\) khi \(x\in\left(-7;-2\right)\cup\left(\dfrac{1}{2};+\infty\right)\). \(f\left(x\right)< 0\) khi \(\left(-\infty;-7\right)\cup\left(-2;\dfrac{1}{2}\right)\). \(f\left(x\right)\) không xác định tại \(x=\left\{\dfrac{1}{2};-2\right\}\)