# Derivative problem

• Sep 27th 2010, 06:34 AM
juventinoalex
Derivative problem
I am trying to use the quotient rule to solve the following problem.

(x^3-5xsqrtx)/x

I know that:
((f)(g)-(f)(g))/g^2 is what I am looking for and this is what I got but it is wrong.

[(3x^2-(5)(1/2sqrtx)(x)-(x^3-5xsqrtx)(1))]/(x^2)

Any help?
Thanks
• Sep 27th 2010, 06:38 AM
mr fantastic
Quote:

Originally Posted by juventinoalex
I am trying to use the quotient rule to solve the following problem.

(x^3-5xsqrtx)/x

I know that:
((f)(g)-(f)(g))/g^2 is what I am looking for and this is what I got but it is wrong.

[(3x^2-(5)(1/2sqrtx)(x)-(x^3-5xsqrtx)(1))]/(x^2)

Any help?
Thanks

The derivative of $5x \sqrt{x}$ is not what you have stated it to be. Note that $5x \sqrt{x} = 5 x^{3/2}$ ....
• Sep 27th 2010, 06:49 AM
juventinoalex
OK so now I have (3x^2-(5x^(3/2))(x)-(x^3-5xsqrtx)(1))/(x^2) but that is still wrong. Do you have any other suggestions? Thanks
• Sep 27th 2010, 07:13 AM
mr fantastic
Quote:

Originally Posted by juventinoalex
OK so now I have (3x^2-(5x^(3/2))(x)-(x^3-5xsqrtx)(1))/(x^2) but that is still wrong. Do you have any other suggestions? Thanks

Yes, differentiate 5x^(3/2).