# Homework Help: Rules for differentiation

1. Mar 10, 2014

### grace77

Problem statement
Find dy/dx

Revelant equations
None

Attempt at a solution

This is what I got to so far but now I'm stuck... Any hints?

2. Mar 10, 2014

### BvU

Do you think you can use the template from now on ?
You need at least one relevant equation, and it is not clear to me what you do in your aattempt. Could you elaborate ?

3. Mar 10, 2014

### SteamKing

Staff Emeritus
It would be less confusing if you wrote y using exponents before doing the differentiation. Check the derivative of the second part of your expression; I think you have an error in the sign.

4. Mar 10, 2014

### grace77

Yes I think I put a negative 1/2 should be a positive

5. Mar 10, 2014

### grace77

Ok I am not sure what equation to use in this though.

6. Mar 10, 2014

### HallsofIvy

You are making a fundamental mistake: the derivative of 1/y is NOT 1 over the derivative of y. Either use the quotient rule to differentiate $\frac{1}{\sqrt{x}}$ or write the whole function as $2x^{1/2}+ x^{-1/2}$ and use the derivative rule $(x^n)'= nx^{n-1}$.

Last edited by a moderator: Mar 10, 2014
7. Mar 10, 2014

### grace77

Thank you I understand it now