Finding the Directional derivative

In summary, the conversation is about finding the directional derivative of a function at a given point. The question is incomplete and the direction is not specified. The directional derivative is the rate of change of a function in a particular direction and there is not enough information to solve the problem.
  • #1
teng125
416
0
Find the directional derivative of f (x, y) = 5−x2−2y2 at P (-1, -1).
anybody pls help as i don't know how to find the direction from this ques so , i can't find the directional derivative


pls help
thanx
 
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  • #2
Your question seems to be incomplete; please provide the complete question as it is given in the book. The directional derivative is the rate at which a function changes at some point in a particular direction.
 
  • #3
neutrino said:
The directional derivative is the rate at which a function changes at some point in a particular direction.

anybody pls help as i don't know how to find the direction from this ques so

I think that's what he's trying to figure out.

If you have absolutely no clue what direction it's in, I would guess that it's in the direction of the vector from the origin to P. Not for any particular reason, but because it's a better guess than anything else :confused:
 
  • #5
One more time: the problem as stated makes no sense. teng125, please state the entire problem as given in your textbook.
 

1. What is a directional derivative?

A directional derivative is a measure of the rate of change of a function in a particular direction.

2. How is the directional derivative calculated?

The directional derivative is calculated by taking the dot product of the gradient of the function and a unit vector in the desired direction.

3. What is the significance of the directional derivative?

The directional derivative helps us understand how a function changes in a specific direction, which can be useful in fields such as physics and engineering.

4. Can the directional derivative be negative?

Yes, the directional derivative can be negative if the function is decreasing in the given direction.

5. Are there any applications of the directional derivative in real life?

Yes, the directional derivative is used in fields such as fluid mechanics, heat transfer, and optimization to analyze the behavior of physical systems.

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