Rút gọn phân thức: 9 - (x+5)^2 / x^2 +4x +4

* Hướng dẫn giải

$\frac{9-{\left(\mathrm{x}+5\right)}^2}{{\mathrm{x}}^2+4\mathrm{x}+4}=\frac{\left(3-\mathrm{x}-5\right)\left(3+\mathrm{x}+5\right)}{{\left(\mathrm{x}+2\right)}^2}=\frac{-\left(\mathrm{x}+2\right)\left(8+\mathrm{x}\right)}{{\left(\mathrm{x}+2\right)}^2}=\frac{-\mathrm{x}-8}{\left(\mathrm{x}+2\right)}$