# Find the first derivative

1. Sep 2, 2006

### Sethka

I've got f(x)=x^2-(7x^2)/2-9x+3

I need to find the first derivative of it but I get as far as 2x- but I'm stumped as to what to do with (7x^2)/2 Would I use the quotiant rule? Or should I somehow bring the 2 up to the top and if so how do I do that?

2. Sep 2, 2006

### loom91

If you mean $$f(x) = x^2 + \frac {7x^2}{2} -9x + 3$$, I'm sure that you can see what the answer will be.

If on the other hand you mean $$f(x) = x^2 + \frac {7x^2}{2 - 9x} + 3$$, use quotient rule.

3. Sep 2, 2006

### Sethka

I guess I risk coming off really stupid but I do mean the first one (7x^2)/2 It looks so simple I know, but i'm not sure which direction to go with the 2. Sorry if I'm wasting your guys' time or anything, but I can't see what the answer should be.

4. Sep 2, 2006

### island-boy

treat 7/2 as a constant (which it is and get the derivative of x^2

5. Sep 2, 2006

### Sethka

Oh! Thank you! Funny how the simplest things can seem so hard. I feel silly now.