Table of contents
- 0. Functions7h 52m
- Introduction to Functions16m
- Piecewise Functions10m
- Properties of Functions9m
- Common Functions1h 8m
- Transformations5m
- Combining Functions27m
- Exponent rules32m
- Exponential Functions28m
- Logarithmic Functions24m
- Properties of Logarithms34m
- Exponential & Logarithmic Equations35m
- Introduction to Trigonometric Functions38m
- Graphs of Trigonometric Functions44m
- Trigonometric Identities47m
- Inverse Trigonometric Functions48m
- 1. Limits and Continuity2h 2m
- 2. Intro to Derivatives1h 33m
- 3. Techniques of Differentiation3h 18m
- 4. Applications of Derivatives2h 38m
- 5. Graphical Applications of Derivatives6h 2m
- 6. Derivatives of Inverse, Exponential, & Logarithmic Functions2h 37m
- 7. Antiderivatives & Indefinite Integrals1h 26m
- 8. Definite Integrals3h 25m
3. Techniques of Differentiation
Basic Rules of Differentiation
Problem 3.9.5
Textbook Question
State the derivative rule for the logarithmic function f(x)=log(subscript b)x. How does it differ from the derivative formula for ln x?
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1
Recall that the derivative of the logarithmic function f(x) = log_b(x) can be expressed using the change of base formula: log_b(x) = ln(x) / ln(b).
Differentiate f(x) = log_b(x) using the quotient rule, which states that if you have a function h(x) = u(x)/v(x), then h'(x) = (u'v - uv')/v^2.
In this case, let u(x) = ln(x) and v(x) = ln(b). The derivative of u(x) is u'(x) = 1/x, and since v(x) = ln(b) is a constant, v'(x) = 0.
Substituting these derivatives into the quotient rule gives f'(x) = (1/x * ln(b) - ln(x) * 0) / (ln(b))^2 = 1 / (x * ln(b)).
In contrast, the derivative of ln(x) is simply 1/x, which shows that the presence of the base b in log_b(x) introduces the factor of 1/ln(b) in the derivative.
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