# What are the first and second derivatives of the function

1. Dec 16, 2003

### roy5995

What are the first and second derivatives of the function

f(x)=(3-x)/(2x+5)

How do i find them, do i use the quotient rule or do i change it to

f(x)=(3-x)*(2x+5)^-1 and use the product rule?

2. Dec 16, 2003

### gnome

Personally I like the product rule better, but you get the same answer either way, so use whichever one you prefer.

3. Dec 16, 2003

### roy5995

I think i got it

f'(x)= -11(2x+5)^-2
f''(x)= 44(2x+5)^-3

but does anyone know of a web site where i can type in the function and it will show me all the max, mins, asymptotes, holes, cusps ...

4. Dec 16, 2003

### gnome

You made a mistake when you combined your terms in the first deriv., & therefore the 2nd is wrong too.

5. Dec 16, 2003

### himanshu121

6. Dec 17, 2003

### faust9

f'(x)= -11(2x+5)^-2
f''(x)= 44(2x+5)^-3

-11 times the quantity (2x+5) to the power of -2 is the correct answer as seen http://home.twmi.rr.com/faust9/calc problem.jpg

f'(x)= -11/(2x+5)^2
f''(x)= 44/(2x+5)^3

and it would be equivalent to what he has above.

Last edited by a moderator: Apr 20, 2017
7. Dec 17, 2003

### himanshu121

Sorry those are not incorrect