Derivatives of Polynomial Functions: Power Rule, Product Rule, and Quotient Rule

Professor Dave Explains
7 Mar 201811:52
EducationalLearning
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TLDRThe video explains techniques for taking derivatives in calculus. It starts by reviewing the power rule and introducing notation for taking derivatives. It then covers derivatives of polynomial functions using the power rule and sum/difference rules. Next, it explains the product rule and quotient rule for finding derivatives of products and quotients of functions. Examples are provided to demonstrate application of these rules. The video emphasizes needing to memorize and practice these derivative rules diligently to be able to find the derivative of any polynomial function.

Takeaways
  • πŸ˜€ The power rule allows us to take the derivative of a function with a positive integer exponent by pulling down the exponent as a coefficient and reducing the exponent by 1
  • 😊 We can use the notation d/dx f(x) as an alternative way to represent taking the derivative of f(x) with respect to x
  • 😎 The sum rule and difference rule allow us to take the derivative of a polynomial term-by-term
  • 🧐 The product rule is used to take the derivative of a product of functions
  • πŸ€“ The quotient rule, which must be memorized, is used to take the derivative of a quotient of functions
  • πŸ˜• The order of terms matters when using the quotient rule but not the product rule
  • 🀩 With an understanding of these basic rules - power, sum, difference, product, and quotient - we can take the derivative of any polynomial
  • πŸ˜€ Negative integer and non-integer exponents can also be handled by the power rule
  • πŸ˜‰ Products and quotients can get more complicated but the associated rules don't really change, just more steps
  • πŸ₯³ With practice, taking derivatives, even of complicated polynomials, is very achievable
Q & A
  • What is the power rule for taking derivatives?

    -The power rule states that to take the derivative of a function involving a positive integer exponent, you pull the exponent down to become a coefficient and reduce the exponent by one.

  • How are the notations f'(x) and d/dx f(x) related?

    -The notations f'(x) and d/dx f(x) are completely identical, both representing the derivative of the function f(x) with respect to x.

  • What is the sum rule when taking derivatives?

    -The sum rule states that the derivative of f(x) + g(x) is equal to the derivative of f(x) plus the derivative of g(x), or (f+g)' = f' + g'.

  • What is the product rule for taking derivatives?

    -The product rule states that the derivative of f(x)*g(x) is equal to f(x)*g'(x) + g(x)*f'(x).

  • Why can't you just multiply the derivatives when taking the derivative of a product?

    -You can't just multiply the derivatives because fg' does not equal f'g'. You have to use the full product rule expression to get the correct derivative.

  • What is the quotient rule for taking derivatives?

    -The quotient rule states that the derivative of f(x)/g(x) is equal to g(x)*f'(x) - f(x)*g'(x) all over [g(x)]^2.

  • Why is order important in the quotient rule?

    -The order matters in the quotient rule because it involves subtraction rather than addition. Switching f'(x) and g'(x) will give an incorrect derivative.

  • How does the power rule apply for negative integer exponents?

    -The power rule works the same for negative integer exponents - you reduce the exponent by 1 and pull the new exponent out front as a coefficient.

  • What makes the derivative of products and quotients more complicated?

    -You can't just multiply or divide functions and use the power rule, you have to apply the specific product and quotient rules which involve more steps.

  • How can you become better at taking derivatives?

    -Taking derivatives gets easier with diligent practice using the power, product, quotient and other rules. Identifying mistakes allows you to reinforce the proper techniques.

Outlines
00:00
πŸ˜€ Introducing Power Rule for Derivatives

This paragraph introduces the power rule for taking derivatives, explaining how to use it to find the derivative of polynomial functions. It covers bringing the exponent down as a coefficient, reducing the exponent by 1, using the notations f'(x) and d/dx, and applying the power rule to examples like x^3 and 3x^4.

05:05
😊 Applying Power Rule to Polynomials

This paragraph explains how to use the power rule to take derivatives of polynomials with multiple terms, using the sum and difference rules. It provides examples of applying these rules to find derivatives term-by-term for more complex polynomial functions.

10:07
πŸ€” Product and Quotient Rules for Derivatives

This paragraph introduces the product rule and quotient rule for finding derivatives. It explains why fg' β‰  f'g' and provides the formulas for the product and quotient rules. Examples are shown for applying these rules to find derivatives of products and quotients of functions.

Mindmap
Keywords
πŸ’‘Differentiation
Differentiation refers to the mathematical concept of finding the derivative or rate of change of a function. In calculus, differentiation helps us understand how a function changes with respect to its inputs. The video relates differentiation to the core idea of calculus and taking derivatives of functions. It shows how grasping this connection enhances understanding of calculus.
πŸ’‘Derivative
The derivative represents the rate of change of a function with respect to its input variable. It measures the sensitivity of the function output to changes in the input. The video introduces notation for derivatives like f'(x) and d/dx and shows how to take derivatives of various polynomial functions using rules like the power rule.
πŸ’‘Power rule
The power rule is a key rule used to find derivatives in calculus. It allows taking the derivative of polynomial terms involving exponents, by reducing the exponent by 1 and bringing the original exponent down as a multiplying coefficient. The video emphasizes learning and applying the power rule to differentiate polynomial functions.
πŸ’‘Sum rule
The sum rule in differentiation states that the derivative of a sum of functions is equal to the sum of their individual derivatives. This allows easily differentiating polynomials by taking derivatives of each term separately. The video uses the sum rule to differentiate polynomials with multiple terms.
πŸ’‘Product rule
The product rule gives the derivative of a product of two functions, in terms of their individual derivatives. Unlike sums, the derivative of a product is not simply the product of individual derivatives. The video introduces the product rule formula and shows examples of differentiating products of functions using it.
πŸ’‘Quotient rule
Similar to products, quotients also have their own rule for differentiation. The quotient rule gives the derivative of a ratio of two functions. The video points out the specific order of terms required in the quotient rule to avoid mistakes in differentiating quotients.
πŸ’‘Algorithm
In this context, an algorithm refers to a step-by-step procedure for performing a specific mathematical operation like differentiation. The power rule, product rule etc serve as algorithms to find derivatives. The video emphasizes learning these algorithms even if the underlying theory is unclear.
πŸ’‘Polynomial
A polynomial function contains terms with varying integer exponents applied to one or more variables. The video focuses on differentiation of various polynomial functions using rules like the power rule, product rule, and sum rule.
πŸ’‘Exponent
The exponent represents the power to which a variable or function is raised in a mathematical expression. The power rule in differentiation uses the exponent of terms in polynomials to determine their derivatives.
πŸ’‘Calculus
Calculus broadly refers to the mathematics of change and motion. Key ideas in calculus are differentiation and integration of functions. The video relates understanding differentiation via derivatives to gaining an enhanced conceptual grasp of calculus.
Highlights

The power rule tells us that in order to take the derivative of some function involving a positive integer exponent, we just pull the exponent down to become a coefficient and then reduce the exponent by one.

d over dx followed by some function means to take the derivative of that function with respect to x.

The sum rule says that the derivative of the quantity f of x plus g of x, will be equal to the derivative of f of x plus the derivative of g of x.

No matter how many terms are in a polynomial, we will just take the derivative of one term at a time.

The product rule says that the derivative of f of x times g of x is equal to (f of x) times (g prime of x) plus (g of x) times (f prime of x).

To find the derivative of f of x over g of x, we find (g of x) times (f prime of x), minus (f of x) times (g prime of x), and all of that will be over g of x quantity squared.

For the product rule, the order of the terms didn't matter, since it involved a sum, but for the quotient rule it will matter.

If you switch the order for the quotient rule, you will get incorrect answers.

As long as we practice and become diligent, we will find that it’s not too difficult to take the derivative of any polynomial.

When using the power rule, this exponent can be a negative integer, or even a non-integer, but the rules don’t really change.

Even when products or quotients get more complicated, it’s not really any harder, just more steps, and therefore more opportunities to make a mistake.

If we practice and become diligent, we will find that it’s not too difficult to take the derivative of any polynomial.

Let's check comprehension.

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