Question

Quy đồng mẫu thức các phân thức:

a,\(\dfrac{x-1}{x^3+1}\),\(\dfrac{2x}{x^2-x+1}\),\(\dfrac{2}{x+1}\)

Answer 1

Có \(\dfrac{x-1}{x^3+1}\) \(=\dfrac{x-1}{\left(x+1\right)\left(x^2-x+1\right)}\)

MTC : \(\text{(x+1)(x^2-x+1)}\)

\(\Rightarrow\dfrac{x-1}{x^3+1}\) \(=\dfrac{x-1}{\left(x+1\right)\left(x^2-x+1\right)}\)

\(\Rightarrow\dfrac{2x}{x^2-x+1}=\dfrac{2x\left(x+1\right)}{\left(x+1\right)\left(x^2-x+1\right)}\)

\(\Rightarrow\dfrac{2}{x+1}=\dfrac{2\left(x^2-x+1\right)}{\left(x+1\right)\left(x^2-x+1\right)}\)