# How to Find the Directional Derivative of h(x, y) = e^(-2x)sin(y) | Summary and Q&A

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March 18, 2020
by
The Math Sorcerer
How to Find the Directional Derivative of h(x, y) = e^(-2x)sin(y)

## TL;DR

The video explains how to find the directional derivative of a function at a specific point in the direction of a given vector using the formula and proper notation.

## Key Insights

• 🇦🇪 The directional derivative of a function can be found using the formula which involves the gradient and a unit vector in the given direction.
• 🫡 The gradient vector is obtained by calculating the partial derivatives of the function with respect to each variable.
• 😥 Plugging in the specific values, including the point and unit vector, allows for the calculation of the directional derivative.
• ❓ Careful attention to notation is essential to accurately solve these problems.
• 🇦🇪 Using a unit vector normalizes the direction and ensures a consistent result across different magnitudes of direction vectors.
• 🫥 The dot product of the gradient vector and the unit vector gives the final result for the directional derivative.
• 😥 The directional derivative measures the rate of change of the function at a given point in a specific direction.

## Transcript

in this video we're going to find the directional derivative of this function at this point in the direction of this vector again we're gonna find the directional derivative of this function at this point in the direction of this vector so there is a formula let me refresh your memory so the directional derivative of a function which we'll call H o... Read More

### Q: What is the formula for finding the directional derivative of a function?

The formula for finding the directional derivative of a function, H, at a point in the direction of a unit vector, U, is the dot product of the gradient of H and U.

### Q: How is the gradient vector calculated?

The gradient vector is calculated by finding the partial derivatives of the function with respect to each variable, denoted as HX and HY.

### Q: What is the significance of using a unit vector?

Using a unit vector in the calculation ensures that the result of the directional derivative is independent of the magnitude of the chosen direction vector.

### Q: Why is proper notation important in these calculations?

Proper notation is crucial to ensure accurate calculations and to avoid errors caused by misinterpreting the variables and notations used in the formula.

## Summary & Key Takeaways

• The video teaches how to find the directional derivative by taking the dot product of the gradient vector and a unit vector in the given direction.

• The gradient vector is computed by finding the partial derivatives of the function with respect to each variable.

• The specific values are plugged into the formula to calculate the directional derivative.