Multicalculus problem.
let f(x,y)=(x-y)/(x+y), find the directions u and the values of Duf(-1/2,3/2) for which
a) Duf(-1/2,3/2) =is largest
b) Duf(-1/2,3/2) = 0
c) Duf(-1/2,3/2)=1

Question

Multicalculus problem.
let f(x,y)=(x-y)/(x+y), find the directions u and the values of Duf(-1/2,3/2) for which
a) Duf(-1/2,3/2) =is largest
b) Duf(-1/2,3/2) = 0
c)  Duf(-1/2,3/2)=1

anonymous · Answer

duf?

anonymous · Answer

directional derivative

anonymous · Answer

any ideas

anonymous · Answer

Df=(2y/((x+y)^2,-2x/(x+y)^2)
(2y/((x+y)^2,-2x/(x+y)^2).(-1/2,3/2)

anonymous · Answer

D=nabla

anonymous · Answer

(2y/((x+y)^2,-2x/(x+y)^2).(-1/2sqrt2,3/2sqrt2)

anonymous · Answer

I think I see what your saying. Thank you

anonymous · Answer

sorry
(2y/((x+y)^2,-2x/(x+y)^2).(-1/sqrt10,3/2sqrt10)

anonymous · Answer

(2y/((x+y)^2,-2x/(x+y)^2).(-1/sqrt10,3/sqrt10)

anonymous · Answer

(:

anonymous · Answer

-2/sqrt10(1/(x+y)) I guess this is the answer..

anonymous · Answer

I just looked at this web site http://tutorial.math.lamar.edu/Classes/CalcIII/DirectionalDeriv.aspx#PD_DirectDeriv_Ex2a