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 Integrals4h 44m
- 9. Graphical Applications of Integrals2h 27m
- 10. Physics Applications of Integrals 2h 22m
3. Techniques of Differentiation
Product and Quotient Rules
Problem 74b
Textbook Question
Tangent lines Suppose f(2)=2 and f′(2) =3. Let g(x) = x²f(x) and h(x) = f(x) / x−3.
b. Find an equation of the line tangent to y = h(x) at x=2.

1
Step 1: Identify the function h(x) = \frac{f(x)}{x - 3} and the point of tangency x = 2.
Step 2: Calculate h(2) using the given f(2) = 2. Substitute x = 2 into h(x) to find h(2).
Step 3: Use the quotient rule to find h'(x). The quotient rule states that if h(x) = \frac{u(x)}{v(x)}, then h'(x) = \frac{u'(x)v(x) - u(x)v'(x)}{(v(x))^2}. Here, u(x) = f(x) and v(x) = x - 3.
Step 4: Calculate h'(2) using the values f(2) = 2, f'(2) = 3, and v(2) = 2 - 3. Substitute these into the derivative found in Step 3.
Step 5: Use the point-slope form of a line, y - y_1 = m(x - x_1), where m = h'(2) and the point (x_1, y_1) is (2, h(2)), to write the equation of the tangent line.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Tangent Line
A tangent line to a curve at a given point is a straight line that touches the curve at that point without crossing it. The slope of the tangent line is given by the derivative of the function at that point. In this case, to find the equation of the tangent line to y = h(x) at x = 2, we need to evaluate h(2) and h'(2).
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Derivative
The derivative of a function measures how the function's output changes as its input changes. It is defined as the limit of the average rate of change of the function as the interval approaches zero. For the function h(x), we need to apply the quotient rule to find h'(x), which will help us determine the slope of the tangent line at x = 2.
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Quotient Rule
The quotient rule is a method for finding the derivative of a function that is the ratio of two other functions. If h(x) = f(x) / g(x), the derivative h'(x) is given by (g(x)f'(x) - f(x)g'(x)) / (g(x))². In this problem, we will apply the quotient rule to differentiate h(x) = f(x) / (x - 3) to find the necessary slope for the tangent line.
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