Help , please ! I don't know

**butbi9x** · October 27th 2008, 01:44 AM

if f(x)= x/(x^2 +1)
(a) find f'(x) and f''(x)

Check to see that your answers to part (a) are reasonable by comparing the graphs of f, f' and f''

Help me !

**mr fantastic** · October 27th 2008, 04:10 AM

Originally Posted by butbi9x

if f(x)= x/(x^2 +1)
(a) find f'(x) and f''(x)

Check to see that your answers to part (a) are reasonable by comparing the graphs of f, f' and f''

Help me !

Start by using the quotient rule to get f'(x).

To get f''(x), use the quotient rule to differentiate f'(x).

**butbi9x** · October 27th 2008, 04:17 AM

I don't understand

**mr fantastic** · October 27th 2008, 04:22 AM

Originally Posted by butbi9x

I don't understand

Then go back to your textbook or class notes and revise the quotient rule and the chain rule. Then read my first post again.

**toraj58** · October 27th 2008, 04:38 AM

if

$h(x) = \frac {f(x)}{g(x)}$

then

$h^\prime(x) = \frac {f^\prime(x)g(x) - g^\prime(x)f(x)}{g^2(x)}$

Thread: Help , please ! I don't know