The partial derivative of f with respect to a variable = (lambda)(partial derivative of g with respect to a variable)
you know what function is F because it is usually given to us as f(x,y,z).
you know what function is G because it is usually set equal to a constant
Find these values for X, Y, Z
plug these X, Y, Z values into the original function G =constant and solve for lambda
We take the value of Lambda that we have obtained and plug it into our original x=, y= and z= values.
This will give us the values of X, Y, Z
We take the X, Y, Z values an plug it into the function F
this will give us A Max or a Min
Usually if the value is a negative it is a minimum
usually if the value is positive it is a maximum