4分数

Let f(x, y):

2² + y²

22²

a. Find the equation of the tangent plane of f at

(1,2).

You answer must be in the form of an equation involving

z., and z.

Do not forget to include "*" to indicate any multiplication

in your equation. Remember that an equation must have

a "=" in it.

To

¹ sin (a)

Əz

sin (a)

[3 points]

b. Approximate f(0.9, 2.1).

f(0.9, 2.1)

f

8z

8

8

a 22

R

52