Consider Figure below. You will notice that this Hyperbolic Paraboloid has the equation z = (x/2)2 - (y/3)2 = (x2/4) - (y2/9). For simplicity we give this function the name f(x, y) so that f(x,y) = (x2/4) - (y2/9).
a. Notice that all of the vertical traces are parabolas whether these vertical traces are in the planes x = a or in the planes y = b, where a and b can be any real numbers. Which of these vertical traces are parabolas opening up and which are parabolas opening down?
b. Is fxx positive or negative?
c. Is fyy positive or negative?