Calculate the directional derivative of the function at the given point in the direction of the vector v. Compute the lo

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Calculate the directional derivative of the function at the given point in the direction of the vector v.
Compute the local maximum and minimum values, and saddle point(s) of the function.
4. Calcule la derivada direccional de la función en el punto dado en la dirección del vector v g(r,s)=tan−1(rs),(1,2),v=5i+10j 5. Calcule los valores máximo y mínimo locales, y punto o puntos sillas de la función. f(x,y)=x3−6xy+8y3