a: \(A=\dfrac{x\left(x+2\right)}{\left(x-2\right)^2}:\dfrac{x^2-4+x+6-x^2}{x\left(x-2\right)}\)
\(=\dfrac{x\left(x+2\right)}{x-2}\cdot\dfrac{x}{x+2}=\dfrac{x^2}{x-2}\)
c: A<0
=>x-2<0
=>x<2
d: B nguyên
=>x^2-4+4 chia hết cho x-2
=>x-2 thuộc {1;-1;2;-2;4;-4}
=>x thuộc {3;1;4;6}