Làm tính trừ: 9x+5/ 2(x-1)(x+3)^2 - 5x-7/2(x-1)(x+3)^2

* Hướng dẫn giải

$\begin{array}{l}\frac{9\mathrm{x}+5}{2\left(\mathrm{x}-1\right){\left(\mathrm{x}+3\right)}^2}-\frac{5\mathrm{x}-7}{2\left(\mathrm{x}-1\right){\left(\mathrm{x}+3\right)}^2}=\frac{9\mathrm{x}+5-5\mathrm{x}+7}{2\left(\mathrm{x}-1\right){\left(\mathrm{x}+3\right)}^2}\\ =\frac{4\mathrm{x}+12}{2\left(\mathrm{x}-1\right){\left(\mathrm{x}+3\right)}^2}=\frac{4\left(\mathrm{x}+3\right)}{2\left(\mathrm{x}-1\right){\left(\mathrm{x}+3\right)}^2}=\frac{2}{\left(\mathrm{x}-1\right)\left(\mathrm{x}+3\right)}\end{array}$