Need help differentiating a function

Click For Summary
SUMMARY

The discussion focuses on differentiating the function f(x) = 2x * (10 - x^2)^(1/2). The correct derivative, f'(x), is derived using the product rule, resulting in f'(x) = -2x^2 * (10 - x^2)^(-1/2). The initial attempt incorrectly treated the variable x as a constant, leading to an erroneous calculation. The importance of applying the product rule correctly is emphasized to avoid such mistakes in differentiation.

PREREQUISITES
  • Understanding of calculus concepts, particularly differentiation.
  • Familiarity with the product rule in calculus.
  • Knowledge of square root functions and their derivatives.
  • Basic algebra skills for manipulating expressions.
NEXT STEPS
  • Study the product rule in calculus for differentiating products of functions.
  • Practice differentiating functions involving square roots and polynomials.
  • Explore common differentiation mistakes and how to avoid them.
  • Learn about the chain rule and its application in complex derivatives.
USEFUL FOR

Students studying calculus, particularly those learning about differentiation techniques, and educators looking for examples of common errors in applying the product rule.

tahayassen
Messages
269
Reaction score
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?
 
Physics news on Phys.org
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.
 
HallsofIvy said:
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!
 

Similar threads

  • · Replies 105 ·
4
Replies
105
Views
11K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K