Thread: Finding a Unit Vector and Direction

Hi,

I need to find the directional derivative of a function. I know how to do this, the problem with this particular question is that the point given is



and the direction given is "toward the origin."

I know to find the directional derivative is simply using the dot product between the gradient of f and the unit vector, but I don't know how to determine what the unit vector here is exactly.

Oh, the function is

f(x,y) = ln sqrt(x^2 + y^2).

Thanks for your help!

Originally Posted by Number42

and the direction given is "toward the origin."

so, use

Originally Posted by FernandoRevilla

so, use

¡Gracias, mi amigo! That is exactly the breakthrough I had been looking for. I've been at this for two days now.

Thank you once again!

Originally Posted by Number42

¡Gracias, mi amigo!

De nada, a mandar.