Thực hiện các phép tính sau: c) 3/ x+1- 2+ 3x/ x^3+1 .

Trả lời

c, $$\begin{gathered} \frac{3}{x+1}-\frac{2+3x}{x^3+1} \\ =\frac{3}{x+1}-\frac{2+3x}{(x+1)(x^2-x+1)} \end{gathered}$$

$=\frac{3(x^2-x+1)-3x-2}{(x+1)(x^2-x+1)}$

$$\begin{gathered} =\frac{3x^2-3x+3-3x-2}{(x+1)(x^2-x+1)} \\ =\frac{3x^2-6x+1}{(x+1)(x^2-x+1)} \end{gathered}$$