A Q Search 14 marks Question 9 (a) Use the Lagrange multiplier method to find the optimum value of the function z, below, subject to the given constraint. z = x4 +4x -5xy + 2y + y2 subject to the constraint y = 100 - 2x. [8 marks] (b) Calculate the value of Lagrange multiplier 1 and verify by recalculating the solution that the value of 1 gives (with a small error) the change in z when the constraint is relaxed by 1 unit. [4 marks] Question 10 Find the stationary points of the function z below and determine whether each is a maximum, minimum or saddle point