# Simplifying fractions with roots

1. Feb 22, 2009

1. The problem statement, all variables and given/known data

Simplify $$\frac{x^2 - \sqrt{x}}{\sqrt{x^5}}$$

2. Relevant equations

Unsure

3. The attempt at a solution

Tried to factorise the numerator and denominator. Not sure how to proceed given the subtraction in the numerator. Best effort so far:

$$\frac{x^2}{\sqrt{x^5}} - \frac{\sqrt{x}}{\sqrt{x^5} }} = \frac{x^2}{x^{ \frac{5}{2}}} - \frac{x^{\frac{1}{2}}} {x^\frac{5}{2}} = x^{ -\frac{1}{2}} - x^{-2} = \frac{1}{x^2} - \frac{1} {\sqrt{x}}$$

which, doesn't seem like much progress from the original equation

2. Feb 22, 2009

### Staff: Mentor

If you multiplied top and bottom by x^(4/5), you'd at least get the radical out of the denominator, which is probably a good thing...

3. Feb 22, 2009

why did you choose $$x^{\frac{4}{5}}$$, or more specifically, how did you decide that value?

4. Feb 22, 2009

### HallsofIvy

Staff Emeritus
yes, that was my question! I would use $x^{4/5}= \sqrt[5]{x^4}$ if I wanted to rationalize $\sqrt[5]{x}$, but this was $\sqrt{x^5}$. Why not multiply numerator and denominator by $\sqrt{x^5}$?

5. Feb 22, 2009

Using $$\sqrt{x^5}$$ in the numerator and denominator sets it up as $$\frac{ (x^2 - x^\frac{1}{2}) x^\frac{5}{2} } { x^\frac{5}{2} x^\frac{5}{2} }$$ and I end up with $$x^{-\frac{1}{2}} - x^{-2}$$. Am I starting off correctly?