a)
\(A=\dfrac{x^2\left(x^2+5x-3\right)-2x\left(x^2+5x-3\right)-4\left(x^2+5x-3\right)+14x-12+ax+y\left(b\right)}{x^2+5x-3}\)\(A=x^2-2x-4+\dfrac{14x-12+ax+y\left(b\right)}{x^2+5x-3}\)
nếu b=y
\(\left\{{}\begin{matrix}a=-14\\b=12\end{matrix}\right.\)
nếu b khác y
a =-14 ; y =12 với mọi b