- #1

- 60

- 0

## Homework Statement

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find directional derivative at point (0,0) in direction u = (1, -1) for

f(x,y) = x(1+y)^-1

## The Attempt at a Solution

grad f(x,y) = ( (1+y)^-1, -x(1+y)^-2 )

grad f(0,0) = (1, 0)

grad f(x,y) . u = (1,0).(1,-1) = 1.

seems easy but markscheme says im wromg. It says answer is 1/root2