Giải các phương trình sau:
a) \(x^3-x^2-\dfrac{8}{x^3-x^2}=2\)
b) \(x\left(\dfrac{8-x}{x-1}\right)\left(x-\dfrac{8-x}{x-1}\right)=15\)
c) \(\left(\dfrac{7x-x^2}{x+1}\right)\left(\dfrac{7+x^2}{x+1}\right)=10\)
d) \(x\left(\dfrac{4-x}{x-3}\right)\left(x+\dfrac{3x-12}{x-3}\right)=4\)
e)\(\left(\dfrac{7x-x^2}{x+3}\right)\left(\dfrac{x^2+21}{x+3}\right)=12\)