Replace beta with '2'

8. Replace B in this question with the second to last digit of your student number. Consider the function f ( x , y ) - x + xy. (a) Suppose that x = (B+2)s- t2 and y = s' + 2t. Use the chain rule for a function of several variables to calculate and (b) Find the equation of the tangent plane to the surface z = f(x, y) at the point with co-ordinates (2, -1, 2)