Finding the derivative of the function

**purplec16** · May 24th 2011, 03:49 PM

$f(x)= \frac{{x}^{3 }-{4x}^{2 }+3 }{x }$

$f'(x)=\f{3x}^{2 }-8x +{x}^{ -2}$

I'm kinda confused on what happens to the x in the denominator i don't know if i should add it or multiply the numerator by it so that is the answer i felt most comfortable

**Mondreus** · May 24th 2011, 03:55 PM

There are two ways to solve it. Either write it as you have and use the quotient rule. Or you can simply use $f(x)=\frac{x^3-4x^2+3}{x}=x^2-4x+\frac{3}{x}$

**purplec16** · May 24th 2011, 03:56 PM

I really dont understand how you got that answer

**purplec16** · May 24th 2011, 03:57 PM

oh ok cool thanks...i understand what you did you divided each term by x

**Mondreus** · May 24th 2011, 03:59 PM

I just wrote f(x) in a different way using basic algebra. You should easily be able to differentiate the second form.

**purplec16** · May 24th 2011, 04:04 PM

so is the answer $f'(x) = 2x-8x-{3x}^{-2 }$

**Mondreus** · May 24th 2011, 04:12 PM

Almost, but the second term is not right.

**purplec16** · May 24th 2011, 04:25 PM

so the answer is:

$f'(x)=2x-8-{3x}^{-2 }$

**Mondreus** · May 24th 2011, 04:31 PM

No. $\frac{d}{dx}\left(-4x\right) \neq -8$

**purplec16** · May 24th 2011, 06:02 PM

sorry -4

Thread: Finding the derivative of the function

LinkBack

Thread Tools

Display

Finding the derivative of the function

Similar Math Help Forum Discussions

Finding the derivative of this function:

Finding derivative of function

Finding the second derivative of a function

Finding a Derivative of a Function

Help with finding the derivative of a logarithmic function

Search Tags