Cogito
Calculus · Chapter 4 · Lesson 2
The Product and Quotient Rules
Products do not differentiate one piece at a time.
12 problems · about 22 minutes · FUN-3.B
Figure — use these to answer the problems
- Point(1, 1)
- Slope of the tangent3
Warm Up
Straightforward practice. Get the method working first.
5 problemsy = x² (3x + 1), so y′ = 9x² + 2x. What is y′ at x = 2?
AnswerWhat is the Product Rule?
- f′g + fg′
- f′g′
y = x², so y′ = 2x. What is y′ at x = 6?
Answery = x² (3x + 1), so y′ = 9x² + 2x. What is y′ at x = 1?
Answery = x³, so y′ = 3x². What is y′ at x = 2?
Answer
Build It Up
The same ideas with more to keep track of.
3 problemsy = 5x⁴, so y′ = 20x³. What is y′ at x = 1?
AnswerIs the derivative of a product the product of the derivatives? 1 for yes, 0 for no.
Answery = (x² + 3x) ÷ x simplifies to x + 3. What is the derivative?
Answer
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
4 problemsMatch each expression with the rule that fits best.
Draw a line from each item on the left to its match on the right.
- x² times (x + 1)
- (x + 1) divided by (x − 1)
- x⁵
- Product Rule
- Quotient Rule
- Power Rule
In the Quotient Rule numerator, which derivative comes first? 1 for the top, 2 for the bottom.
AnswerThe Check
y = x · x. Using the Product Rule, what is the derivative at x = 3?
AnswerThe Simplification
y = (x³ + x) ÷ x simplifies to x² + 1. What is the derivative at x = 4?
Answer