Thực hiện các phép cộng, trừ phân thức sau:; c) 4/x^2-1-2/x^2+x .

Trả lời

c) $\frac{4}{x^2-1}-\frac{2}{x^2+x}$

$=\frac{4}{\left(x+1\right)\left(x-1\right)}-\frac{2}{x\left(x+1\right)}$

$=\frac{4x}{x\left(x+1\right)\left(x-1\right)}-\frac{2\left(x-1\right)}{x\left(x+1\right)\left(x-1\right)}$

$=\frac{4x-\left(2x-2\right)}{x\left(x+1\right)\left(x-1\right)}$$=\frac{4x-2x+2}{x\left(x+1\right)\left(x-1\right)}$

$=\frac{2x+2}{x\left(x+1\right)\left(x-1\right)}$

$=\frac{2\left(x+1\right)}{x\left(x+1\right)\left(x-1\right)}$