3. Find and classify the stationary point(s) of the following functions: (a k : R' - R defined by: k (2) = 2 Ax + b, (4) where: A = -1 3 1 (5) 1 -3 and b = 2. Is k (x) a quadratic form? (b) 1: R2 - R defined by: I(a = 1e 21(x2 - 4x2). (6) Are any of the stationary points of I(x) global extrema? Why /why not