Calculus

[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?

[gnome]

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

[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 ...

[gnome]

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

[himanshu121]

You haven't applied the Product Rule properly

http://www.math.temple.edu/~cow/

[faust9]

How are roy's answers incorrect?

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 HERE: (http://home.twmi.rr.com/faust9/calc%20problem.jpg)

roy's answer could be written:

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

and it would be equivalent to what he has above.

[himanshu121]

Sorry those are not incorrect