SOLUTION: Identify a vector perpendicular to the surface f(x,y)= 4-x^2-2y^2 at (1,1,1)

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Question 873661: Identify a vector perpendicular to the surface
f(x,y)= 4-x^2-2y^2 at (1,1,1)
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Find the partial derivative with respect to x and y.
f%5Bx%5D and f%5By%5D
The normal vector is (f%5Bx%5D,f%5By%5D,-1)
f%5Bx%5D=-2x
f%5By%5D=-4y
So then,
N=(-2x,-4y,-1)
N(1,1,1)=(-2,-4,1)