\(A=\left[\dfrac{5}{x+3}-\dfrac{5\left(x-3\right)}{2x-9}\cdot\dfrac{2x-9+\left(-2x+9\right)\left(x^2-9\right)}{x^2-9}\right]:\dfrac{1-x}{1+x}\)
\(=\left[\dfrac{5}{x+3}-\dfrac{5}{2x-9}\cdot\dfrac{\left(2x-9\right)\left(1-x^2+9\right)}{x+3}\right]\cdot\dfrac{x+1}{-x+1}\)
\(=\left(\dfrac{5}{x+3}-\dfrac{5\left(10-x^2\right)}{x+3}\right)\cdot\dfrac{x+1}{-x+1}\)
\(=\dfrac{5-50+5x^2}{x+3}\cdot\dfrac{x+1}{-x+1}\)
\(=\dfrac{5\left(x-3\right)\left(x+3\right)}{\left(x+3\right)}\cdot\dfrac{x+1}{-x+1}\)
\(=\dfrac{-5\left(x-3\right)\left(x+1\right)}{x-1}\)
Đúng 0
Bình luận (0)
