Find three posie numbers whose sum is 18 and whose product is a maximum I Let x be the first number, let y be the second number, and let z be the third number. Construct f(x,y,z) and g(x,y,z), the two functional parts of the Lagrange function, F(x,y,Z,1) =1(x,y,Z) - 1 g(x,y,Z) F(x,y,z) = g(x,y,Z) =