Question

Giúp vs ạ

Answer 1

a: \(\frac{-6}{x+3}+\frac{x+3}{x^2-9}+\frac{x-4}{x-3}\)

\(=\frac{-6\left(x-3\right)+x+3+\left(x-4\right)\left(x+3\right)}{\left(x-3\right)\left(x+3\right)}\)

\(=\frac{-6x+18+x+3+x^2-x-12}{\left(x-3\right)\left(x+3\right)}=\frac{x^2-6x+9}{\left(x-3\right)\left(x+3\right)}\)

\(=\frac{\left(x-3\right)^2}{\left(x-3\right)\left(x+3\right)}=\frac{x-3}{x+3}\)

b: \(\frac{x^3-5x^2+15x-27}{x-3}\)

\(=\frac{x^3-3x^2-2x^2+6x+9x-27}{x-3}\)

\(=\frac{x^2\left(x-3\right)-2x\left(x-3\right)+9\left(x-3\right)}{x-3}=x^2-2x+9\)