Cogito
AP Calculus AB · Chapter 3 · Lesson 2
The Chain Rule
Rates multiply along a chain.
12 problems · about 22 minutes · FUN-3.C
Figure — use these to answer the problems
- Point(1, 1)
- Slope of the tangent2
Warm Up
Straightforward practice. Get the method working first.
5 problemsFor (6x + 1)³, what is the inner derivative?
AnswerWhat is the most common Chain Rule error?
- Forgetting to multiply by the inner derivative.
- Using the wrong power.
For (2x + 7)⁴, the inner derivative?
AnswerFor (x² + 1)³, the inner derivative at x = 2?
Answery = (3x + 1)⁵, so y′ = 15(3x + 1)⁴. What is y′ at x = 0?
Answer
Build It Up
The same ideas with more to keep track of.
3 problemsFor (4x − 9)⁷, the inner derivative?
AnswerThree nested layers means how many factors multiplied?
AnswerFor (x + 5)⁹, the inner derivative?
Answer
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
4 problemsPut the Chain Rule process in order.
Write 1 to 4 in the boxes to put these in order.
- Identify the outer and inner functions.
- Differentiate the outer, leaving the inside untouched.
- Differentiate the inner function.
- Multiply the two results together.
y = (2x)³ expands to 8x³, so y′ = 24x². What is y′ at x = 1?
AnswerThe Inside
For (5x − 2)³, what is the derivative of the inside?
AnswerThe Chain
y changes 4 times as fast as u, and u changes 3 times as fast as x. How many times as fast as x does y change?
Answer