The Quotient Rule: Not Just Dividing Derivatives But Simple Enough
The quotient rule for derivatives allows calculation of the derivative of a function divided by another. It is essential because the derivative of a quotient of two functions isn't simply the quotient of their derivatives, necessitating a distinct formula for accurate differentiation in various applications.

Definition:
To use quotient rule, you subtract the product of the bottom function and the derivative of the top from the product of the top and the derivative of the bottom, then divide it all by the bottom function squared. Here is the mathematical formula for the quotient rule:
\( \left(\frac{f}{g}\right)’ = \frac{f’g – fg’}{g^2} \)
Example 1:
Let’s solve an example.
\( f(x) = \sin x, \ g(x) = x^2 + 1\)
\( f'(x) = \cos x, \ g'(x) = 2x \)
\(\Rightarrow \left(\frac{\sin x}{x^2 + 1}\right)’ = \frac{\cos x \cdot (x^2 + 1) – \sin x \cdot 2x}{(x^2 + 1)^2} \)
\( = \frac{\cos x \cdot x^2 + \cos x – 2x \sin x}{(x^2 + 1)^2} \)
Example 2:
\( f(x) = x^3, \ g(x) = \cos x \)
\(f'(x) = 3x^2, \ g'(x) = -\sin x \)
\(\Rightarrow \left(\frac{x^3}{\cos x}\right)’ = \frac{3x^2 \cdot \cos x – x^3 \cdot (-\sin x)}{\cos^2 x} \)
\( = \frac{3x^2 \cos x + x^3 \sin x}{\cos^2 x} \)
Hints:
- In some complex fractions, applying logarithmic differentiation simplifies the process more than the quotient rule would.
- For \( \frac{1}{x} \) and \( \frac{1}{f(x)} \) , we use the following formulas, although \( \frac{1}{x} \) could be solved using power rule too.
\( \left(\frac{1}{x}\right)’ = -\frac{1}{x^2} \)
\( \left(\frac{1}{f(x)}\right)’ = -\frac{f'(x)}{[f(x)]^2} \)
Related to This Article
More math articles
- 10 Best Math Apps for Middle School That Make Learning Fun
- FREE 8th Grade MCAS Math Practice Test
- How to Prepare for Math Exams: Study Tips & Tricks
- Money and Decimals Relation: A Step-by-Step Guide
- Estimation Expedition: How to Solve Word Problems with Approximate Sums and Differences
- 4th Grade FSA Math FREE Sample Practice Questions
- 10 Most Common 8th Grade ACT Aspire Math Questions
- The Ultimate SSAT Upper-Level Math Course (+FREE Worksheets)
- FTCE Test Facts and FAQs
- 8th Grade Georgia Milestones Assessment System Math Worksheets: FREE & Printable
What people say about "The Quotient Rule: Not Just Dividing Derivatives But Simple Enough - Effortless Math: We Help Students Learn to LOVE Mathematics"?
No one replied yet.