Algebra Equations Problem

Exercise 1
You shall answer one and only one of the questions below. If you answer more
than one of the questions, only the question with the lowest number will be
graded.
(i) Compute the equation of the tangent plane to the graph of the function
f(x, y) = 3.c´y – 2y3
(1)
at the point (1,1,1).