Find a vector u for which Duf(1,1) =0

Thank you.

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- May 1st 2008, 11:53 PMal1850Directional derivatives
Find a vector u for which Duf(1,1) =0

Thank you. - May 2nd 2008, 01:24 AMCaptainBlack
- May 2nd 2008, 01:28 AMal1850
- May 2nd 2008, 01:53 AMDanshader
well first for the definition of directional derivative:

directional derivative of a scalar function, in the direction of a unit vector, at a point is given by:

in your question:

at f(1,1):

therefore from;

now to obtain a zero and must be equal in magnitude but opposite in sign:

n can take any value.

Unit vector of

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