Example: One variable.

   y:= (x-1)*(1-x)*(x-2);
   extrema(y,{},{x},'cp'); # Compute extreme value of y
   evalf(%);  # Answer in decimal form
   cp;  # Variable cp contains the critical points of y
   evalf(cp); # Print in decimal form


Example: Two variables

   unassign('x','y'): z:= (1-x)*(2-y)*(1-y)^2;
   extrema(z,{},{x,y},'cp');
   evalf(%); # Print in decimal form
   cp;  # Print the critical points of z
   evalf(cp); # Print in decimal form


 Maximize and Minimize Functions
   These Maple functions find the minima and maxima and omit any other
   possible critical points. The functions have existed as part of the
   Maple kernel since Ver 7 of Maple. Examples:

  minimize(cos(x),x=1..3); # Answer cos(3)
  maximize(cos(x),x=1..3); # Answer cos(1)
  minimize(x^2-3*x+y^2+3*y+3, location); 
    # Answer -3/2, {[{x = 3/2, y = -3/2}, -3/2]}