a, A = \(\left(\dfrac{x^2-3}{x^2-9}+\dfrac{1}{x-3}\right):\dfrac{x}{x+3}\)
b, B = \(\left(\dfrac{x-1}{x+2}+\dfrac{x}{2-x}\right):\dfrac{3}{x^2-4}\)
c, C = \(\left(\dfrac{15-x}{x^2-25}+\dfrac{2}{x+5}\right):\dfrac{x+1}{2x^2-10x}\)
d, D = \(\left(\dfrac{x+3}{x^2-1}-\dfrac{3}{x+1}\right):\left(1-\dfrac{2}{x-1}\right)\)
a: \(A=\dfrac{x^2-3+x+3}{\left(x-3\right)\left(x+3\right)}\cdot\dfrac{x+3}{x}\)
\(=\dfrac{x\left(x+1\right)}{x+3}\cdot\dfrac{1}{x}=\dfrac{x+1}{x+3}\)
b: \(B=\dfrac{\left(x-1\right)\left(x-2\right)-x\left(x+2\right)}{\left(x-2\right)\left(x+2\right)}\cdot\dfrac{\left(x-2\right)\left(x+2\right)}{3}\)
\(=\dfrac{x^2-3x+2-x^2-2x}{3}=\dfrac{-5x+2}{3}\)
c: \(C=\dfrac{15-x+2x-10}{\left(x-5\right)\left(x+5\right)}\cdot\dfrac{2x\left(x-5\right)}{x+1}\)
\(=\dfrac{x+5}{\left(x+5\right)}\cdot\dfrac{2x}{x+1}=\dfrac{2x}{x+1}\)
