- #1

Cpt Qwark

- 45

- 1

## Homework Statement

For [tex]f(x,y)=x^2-xy+y^2[/tex] and the vector [tex]u=i+j[/tex].

ii)Find two unit vectors such [tex]D_vf=0[/tex]

## Homework Equations

N/A.

## The Attempt at a Solution

Not sure if relevant but the previous questions were asking for the unit vector

**u**- which I got [tex]\hat{u}=\frac{1}{\sqrt{2}}(i+j)[/tex] for the maximum value of [tex]D_uf[/tex] which was [tex]\sqrt{2}[/tex].