# Homework Help: Differentiation - Quotient rule

1. Jan 5, 2010

### zebra1707

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

Given y = x^2 + 6 / x find x if dy/dx equals 0 zero

2. Relevant equations

dy/dx = v du/dx - u dv/dx / v^2

3. The attempt at a solution

I have got as far as dy/dx = x^2 - 6 / x^2

However then zero must equal Sqrt 6, which 2.44.... - can someone please confirm.

Many thanks.

2. Jan 5, 2010

### rock.freak667

I didn't check to see if your derivative is correct, but I will assume it is. But solving x2-6=0 yields two answers √6 and -√6 . You have two answers for x.

3. Jan 5, 2010

### zebra1707

Hi Rock freak

dy/dx = x^2 - 6 all over x^2

So not sure how you arrived at x^2 - 6 = Sqrt +/- 6

Can you check my derivative calc.

Cheers

4. Jan 5, 2010

### rock.freak667

$$\frac{x^2-6}{x^2}=0 \Rightarrow x^2-6=0$$