Tangent Plane And Normal Vector.

by dcl
Tags: normal, plane, tangent, vector
 P: 55 I'm having trouble working out the tangent plane of an equation at a specified point (4,1,-2) The equation being $$9x^2 - 4y^2 - 25z^2 = 40$$ now $$\nabla f = (18x, -8y, -50z)$$ yeh? Just reading off this should give us the normal vector shouldn't it? (18,-8,-50) and from that we can work out the equation of the plane. 18(x-4) - 8(y-1) -50(z-(-2)) = 0 Is this corrent or am I using a horribly flawed method?