find an equation of the tangent plane to the given surface a

find an equation of the tangent plane to the given surface at the specified point.

z=(xy)^1/2 Point(1,1,1)

Since z = x^(1/2) y^(1/2), we have ?z = <(1/2) x^(-1/2) y^(1/2), (1/2) x^(1/2) y^(-1/2)>
==> ?z(1,1) = <1/2, 1/2>.

Therefore, the equation of the tangent plane is
z - 1 = (1/2)(x - 1) + (1/2)(y - 1).