Answer:
4th option (sqrt(10))/2
Step-by-step explanation:

The answer is b because the answer is b and the people don’t know how to do it
The formula of an area of a square: 
a - side
We have: 
substitute:

The fromula of a perimeter of a square is: 
substitute:

The tangent to
through (1, 1, 1) must be perpendicular to the normal vectors to the surfaces
and
at that point.
Let
. Then
is the level curve
. Recall that the gradient vector is perpendicular to level curves; we have

so that the gradient of
at (1, 1, 1) is

For the surface
, we have

so that
. We can obtain a vector normal to
by taking the cross product of the partial derivatives of
, and evaluating that product for
:


Now take the cross product of the two normal vectors to
and
:

The direction of vector (24, 8, -8) is the direction of the tangent line to
at (1, 1, 1). We can capture all points on the line containing this vector by scaling it by
. Then adding (1, 1, 1) shifts this line to the point of tangency on
. So the tangent line has equation

Answer:
I'm sorry I don't know the first one but the second one is (-3x^2b^3)^3
Step-by-step explanation: