Question

By Leibniz' rule, write the formula for \(\left(d^{n} / d x^{n}\right)(u v)\).

Short answer

The nth derivative formula by Leibniz's rule is \[\frac{d^n}{dx^n}(u v) = \sum_{k=0}^{n} \binom{n}{k} \frac{d^{n-k}u}{dx^{n-k}} \frac{d^k v}{dx^k}.\]

Step-by-step solution

Understand Leibniz's Rule

Leibniz's rule is used to find the nth derivative of a product of two functions. It’s a generalization of the product rule for derivatives.

Recall the Formula

The formula for the nth derivative of the product of two functions is: \[\frac{d^n}{dx^n}(u v) = \sum_{k=0}^{n} \binom{n}{k} \frac{d^{n-k}u}{dx^{n-k}} \frac{d^k v}{dx^k}.\] This means you take the sum of the products of the binomial coefficient, the (n-k)th derivative of u, and the kth derivative of v for k ranging from 0 to n.

Explain the Components

In the formula, \(\binom{n}{k}\) is the binomial coefficient, which is calculated as \(\binom{n}{k} = \frac{n!}{k!(n-k)!}\). Additionally, \( \frac{d^{n-k}u}{dx^{n-k}} \) is the (n-k)th derivative of u with respect to x, and \( \frac{d^{k}v}{dx^{k}} \) is the kth derivative of v with respect to x.

Summarize the Application

To apply Leibniz's rule, compute the necessary derivatives of u and v, then multiply these derivatives by the corresponding binomial coefficients, and finally sum all these products from k = 0 to n.

Key concepts

product rule

The product rule is a fundamental concept in calculus used to find the derivative of the product of two functions. For functions u(x) and v(x), the product rule states that: \[ \frac{d}{dx}(uv) = u\frac{dv}{dx} + v\frac{du}{dx} \]. This tells us that the derivative of a product is not simply the product of the derivatives. Instead, we multiply each function by the derivative of the other function and add the results.
Leibniz's rule generalizes this idea to the nth derivative of a product. Instead of using just the first derivatives, we use higher-order derivatives with binomial coefficients to find the nth derivative of the product. This advanced rule allows us to handle more complex scenarios where the functions and their derivatives need to be analyzed in detail.