Need help differentiating a function

  • Thread starter tahayassen
  • Start date
  • #1
269
1

Homework Statement



f(x) = 2x * (10-x^2)^(1/2)

Determine f'(x).

2. The attempt at a solution

f'(x) = 2x*(1/2) * (10-x^2)^(-1/2) * (-2x)
= x * (-2x) * (10-x^2)^(-1/2)
= -2x^2 * (10-x^2)^(-1/2)

What am I doing wrong?
 

Answers and Replies

  • #2
HallsofIvy
Science Advisor
Homework Helper
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You aren't using the product rule. You have multiplied x by the derivative of [itex](10- x^2)^{1/2}[/itex], effectively treating that first "x" as though it were a constant. It is not.
 
  • #3
269
1
You aren't using the product rule. You have multiplied x by the derivative of [itex](10- x^2)^{1/2}[/itex], effectively treating that first "x" as though it were a constant. It is not.

Doh! I'm such an idiot! Thanks for the quick response!
 

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