Thực hiện các phép tính sau: 27-x^3/ 5x+ 5 : 2x-6/ 3x + 3

* Hướng dẫn giải

$\begin{array}{l}\frac{27-{\mathrm{x}}^3}{5\mathrm{x}+5}:\frac{2\mathrm{x}-6}{3\mathrm{x}+3}=\frac{\left(3-\mathrm{x}\right)\left(9+3\mathrm{x}+{\mathrm{x}}^2\right)}{5\left(\mathrm{x}+1\right)}.\frac{3\left(\mathrm{x}+1\right)}{-2\left(3-\mathrm{x}\right)}\\ =\frac{\left({\mathrm{x}}^2+3\mathrm{x}+9\right)\left(-3\right)}{2.5}=\frac{-3\left({\mathrm{x}}^2+3\mathrm{x}+9\right)}{10}\end{array}$