# Math Help - Tangent plane

1. ## Tangent plane

Find the equation of the tangent plane at (3,4,1) to the surface x^2+y^2-xyz=13. View the surface as the graph of a function of two variables z=g(x,y).

2. ## Re: Tangent plane

Originally Posted by mgwalker
Find the equation of the tangent plane at (3,4,1) to the surface x^2+y^2-xyz=13. View the surface as the graph of a function of two variables z=g(x,y).
I did not check to see if that point is on the surface.
$\Delta F(x,y,z)=<2x-yz,2y-xz,-xy>$

Now the tangent plane is:
$\Delta F(3,4,1)\cdot =0$