Question 5

Find f,(x,y) and f (x,y), and explain why f(x y) has no local extrema f(x,y) =6x +4y +2. fx ( x,y ) fy ( x .y ) Choose the best explanation below for the reason that f(x,y) has no local extrema O A. The functions fx (x,y) and fy (x,y) are never equal to each other. O B. The functions fx (x,y) and fy (x,y) are non-zero for all (x,y) O C. The functions fx (x,y) and fy(x,y) have no local extrema O D. The second derivative test fails because AC - B