Question

\(\dfrac{-4x^2}{x^2-25}\)-\(\dfrac{2x^2+x}{x^2-25}\)-\(\dfrac{2x}{5-x}\)

Answer 1

Ta có: \(\dfrac{-4x^2}{x^2-25}-\dfrac{2x^2+x}{x^2-25}-\dfrac{2x}{5-x}\)

\(=\dfrac{-4x^2-2x^2-x}{\left(x-5\right)\left(x+5\right)}+\dfrac{2x}{x-5}\)

\(=\dfrac{-6x^2-x}{\left(x-5\right)\left(x+5\right)}+\dfrac{2x\left(x+5\right)}{\left(x-5\right)\left(x+5\right)}\)

\(=\dfrac{-6x^2-x+2x^2+10x}{\left(x-5\right)\left(x+5\right)}\)

\(=\dfrac{-4x^2+9x}{\left(x-5\right)\left(x+5\right)}\)