Exercise 1 Find the maximum and minimum of the function f(x,y)=x-2(a+b+c)x-3y and (0,20+2b+2c) +6(a+b+c)y+abc on the closed triangle with vertices (0,0), (20+2b+20,0) Exercise 2 Find the points on the surface y=a+b+c+x+z+xz that are closest to the origin. Exercise 3 Find the extreme values of the function fixy.z)-xyz subject to x++-6(a+b+c) Indicate whether the points you have found are minima or maxima. Attach File