To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x^{2}$ and $x$ is $x^{2}$. Multiply $\frac{12\left(x^{2}+1\right)}{x}$ times $\frac{x}{x}$.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x^{2}$ and $x$ is $x^{2}$. Multiply $\frac{12\left(x^{2}+1\right)}{x}$ times $\frac{x}{x}$.