Science:Math Exam Resources/Courses/MATH200/December 2013/Question 01 (e)/Statement

Suppose it is known that the direction of the fastest increase of the function $\displaystyle f(x,y)$ at the origin is given by the vector $\displaystyle \langle 1,2\rangle$. Find a unit vector $\displaystyle {\textbf {u}}$ that is tangent to the level curve of $\displaystyle f(x,y)$ that passes through the origin.