- Explain and use the chain rule
- Use the chain rule along with other rules to differentiate functions involving powers, products, quotients, and trigonometry
- Use the chain rule to find derivatives when multiple functions are nested together
Deriving the Chain Rule
The Main Idea
- Chain Rule Definition:
- For h(x)=f(g(x)), the derivative is: h′(x)=f′(g(x))⋅g′(x)
- Alternative Notation:
- If y is a function of u, and u is a function of x: dydx=dydu⋅dudx
- Purpose:
- Simplifies differentiation of composite functions
- Breaks down complex functions into simpler parts
- Useful for functions like sin(x3) or √3x2+1
- Chain rule can be applied iteratively for functions with multiple compositions
Differentiate h(x)=esin(x2) using the chain rule.
Combining the Chain Rule With Other Rules
The Main Idea
- Chain Rule with Power Rule:
- For h(x)=(g(x))n, the derivative is: h′(x)=n(g(x))n−1g′(x)
- Chain Rule with Trigonometric Functions:
- Example: ddx(sin(g(x)))=cos(g(x))g′(x)
- Chain Rule with Product Rule:
- Apply product rule first, then chain rule to each term
- General Strategy:
- Identify the composition of functions
- Apply appropriate rules in the correct order
- Simplify the result
Find the derivative of h(x)=(2x3+2x−1)4
Find the equation of the line tangent to the graph of f(x)=(x2−2)3 at x=−2.
Find the derivative of h(x)=sin(7x+2).
Find the derivative of h(x)=x(2x+3)3
Applying the Chain Rule Multiple Times
The Main Idea
- Chain Rule for Composition of Three Functions:
- For k(x)=h(f(g(x))), the derivative is: k′(x)=h′(f(g(x)))⋅f′(g(x))⋅g′(x)
- General Approach:
- Work from the outside in
- Apply the chain rule as many times as necessary
- Number of Terms:
- The derivative of a composition of n functions will have n terms
Find the derivative of h(x)=sin6(x3)
A particle moves along a coordinate axis. Its position at time t is given by s(t)=sin(4t). Find its acceleration at time t.
Let h(x)=f(g(x)). If g(2)=−3,g′(2)=4, and f′(−3)=7, find h′(2).
Find the derivative of y=ln(sin(e2x)).
The Chain Rule Using Leibniz’s Notation
The Main Idea
- Leibniz’s Notation for Chain Rule:
- For y=f(u) and u=g(x), the chain rule is expressed as: dydx=dydu⋅dudx
- Interpretation:
- dydx: Rate of change of y with respect to x
- dydu: Rate of change of y with respect to u
- dudx: Rate of change of u with respect to x
- Advantages:
- Provides a clear visual representation of the chain rule
- Helps in understanding the relationship between variables
Use Leibniz’s notation to find the derivative of y=cos(x3). Make sure that the final answer is expressed entirely in terms of the variable x.
Find the derivative of y=√sin(2x3) using Leibniz’s notation.