Giải phương trình
a) \(\dfrac{12}{1-9x^2}\)=\(\dfrac{1-3x}{1+3x}\)-\(\dfrac{1+3x}{1-3x}\)
b) \(\dfrac{2}{x^2-4}\)-\(\dfrac{x-1}{x\left(x-2\right)}\)+\(\dfrac{x-4}{x\left(x+2\right)}\)=0
c)\(\dfrac{16}{x^2-16}\)+\(\dfrac{2}{x+4}\)-\(\dfrac{1}{x-4}\)=0
d)\(\dfrac{x}{x-3}\)-\(\dfrac{x}{x-5}\)=\(\dfrac{x}{x-4}\)-\(\dfrac{x}{x-6}\)