How to Correctly Take the Derivative of a Fraction with a Quadratic Denominator

  • Thread starter Thread starter PhizKid
  • Start date Start date
  • Tags Tags
    Derivative
Click For Summary
SUMMARY

The discussion focuses on calculating the derivative of the function \(\frac{y - 1}{y^2 - y + 1}\). The correct derivative is established as \(\frac{y^2 - 2y}{(y^2 - y + 1)^2}\), derived using the quotient rule, which is defined as \(\frac{d}{dx}\frac{f(x)}{g(x)} = \frac{g(x)f'(x) - f(x)g'(x)}{g(x)^2}\). A participant initially miscalculated the derivative, mistakenly introducing a fourth power in the numerator, but later recognized the error. The discussion also touches on the product rule as an alternative method for differentiation.

PREREQUISITES
  • Understanding of calculus, specifically differentiation techniques
  • Familiarity with the quotient rule for derivatives
  • Knowledge of the product rule for derivatives
  • Ability to manipulate algebraic expressions involving powers
NEXT STEPS
  • Review the quotient rule for derivatives in calculus
  • Study the product rule and its applications in differentiation
  • Practice solving derivatives of rational functions
  • Explore common mistakes in derivative calculations and how to avoid them
USEFUL FOR

Students studying calculus, educators teaching differentiation techniques, and anyone seeking to improve their understanding of derivative calculations involving rational functions.

PhizKid
Messages
477
Reaction score
2

Homework Statement


Derivative of \frac{y - 1}{y^2 - y + 1}


Homework Equations





The Attempt at a Solution


d9DY1.png


The solution is \frac{y^2 - 2y}{(y^2 - y + 1)^2} but in my work, the answer will have something to the 4th power on the top which will be impossible to cancel out. What have I done wrong?

Edit: Never mind, I see my mistake
 
Last edited:
Physics news on Phys.org
Remember: \frac{d}{dx}\frac{f(x)}{g(x)} = \frac{g(x)f'(x) - f(x)g'(x)}{g(x)^2}
 
Yes but I don't like to work with the quotient rule. I should be getting the same answer using the product rule anyway, right?

Edit: Never mind, I see my mistake
 
That's fine.

Then, remember: -(y^2-y+1)^{-2} = -\frac{1}{(y^2-y+1)^2}
(An expression to the -2 power doesn't equal 1/sqrt(expression))
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 6 ·
Replies
6
Views
2K
Replies
2
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
9
Views
2K
Replies
2
Views
1K
  • · Replies 24 ·
Replies
24
Views
3K
  • · Replies 48 ·
2
Replies
48
Views
5K
  • · Replies 4 ·
Replies
4
Views
1K