# Homework Help: Find the second derivate .(tricky question).

1. Jun 18, 2009

### Penultimate

There Fx a twice derivable function. Find Y'' if $$Y=f(\frac{2}{x})$$

2. Jun 18, 2009

### Pengwuino

You need to show some work first. Do you know the chain rule?

3. Jun 18, 2009

### Penultimate

I have problems with english ezpresions about math and i am not sure what you refer with chain rule.

4. Jun 18, 2009

### Pengwuino

The "chain rule" can be summarized as $$\frac{{df}}{{dx}} = \frac{{df}}{{du}}\frac{{du}}{{dx}}$$. Make the substitution $$u = \frac{2}{x}$$ and you can take derivatives of f(2/x). Remember, f(2/x) is any arbitrary function with 2/x as the argument so when you find your result, don't be surprised that you have arbitrary derivatives, that is terms including f'(2/x) and f''(2/x).

5. Jun 18, 2009

Penultimate: You have at least 5 or 6 of these threads. No attempts at anything in any of them. We do not do your work for you, regardless of "how much time you have or do not have ."

Don't be lazy and show some effort.

6. Jun 18, 2009

### Penultimate

Saladsamurai i know i and wish could but yesterday i got these question and tomomorow i have got the analysis exam. I dont expect you to do my homework , but i still hope you would solve the problem i have submited.
I dont know what else to say , whatever you will do with my threads i thank you again for the patience you are showing. Good night everybody have a nice time.

7. Jun 19, 2009