I have $$\frac{x^4+2x}{x^4}$$ which becomes $$\frac{x^3+2}{x^3}$$ after pulling out the common factor. I wanted to know why you you don't simplify $\frac{x^4+2x}{x^4}$ to $2x$ and the two $x^4$ cancel each other out, or is this because you must apply the denominator fraction to all numerator parts? So $\frac{x^4}{x^4}$ and $\frac{2x}{x^4}$ which doesn't work.