To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x$ and $\left(x^{2}+1\right)\times 2$ is $2x\left(x^{2}+1\right)$. Multiply $\frac{x^{2}+1}{x}$ times $\frac{2\left(x^{2}+1\right)}{2\left(x^{2}+1\right)}$. Multiply $\frac{x\times 5}{\left(x^{2}+1\right)\times 2}$ times $\frac{x}{x}$.
Since $\frac{\left(x^{2}+1\right)\times 2\left(x^{2}+1\right)}{2x\left(x^{2}+1\right)}$ and $\frac{x\times 5x}{2x\left(x^{2}+1\right)}$ have the same denominator, add them by adding their numerators.
To add or subtract expressions, expand them to make their denominators the same. Least common multiple of $x$ and $\left(x^{2}+1\right)\times 2$ is $2x\left(x^{2}+1\right)$. Multiply $\frac{x^{2}+1}{x}$ times $\frac{2\left(x^{2}+1\right)}{2\left(x^{2}+1\right)}$. Multiply $\frac{x\times 5}{\left(x^{2}+1\right)\times 2}$ times $\frac{x}{x}$.
Since $\frac{\left(x^{2}+1\right)\times 2\left(x^{2}+1\right)}{2x\left(x^{2}+1\right)}$ and $\frac{x\times 5x}{2x\left(x^{2}+1\right)}$ have the same denominator, add them by adding their numerators.