How to find the vertex coordinates in junior high school mathematics must be transformed into a general formula?
To find the vertex coordinates of the maximum profit y = (56-2x) (120+6x), there is no need to turn it into a general formula. We can use (56-2x) (120+6x) = 0 to find X 1 = 28, X2 =-20, then the symmetry axis X = (X 1+X2)/2 = 4. Therefore, the abscissa of the vertex is x = 4. Substitute x = 4 for y = (56-2x) (120+6x) = (56-2× 4) (120+6× 2) = 48×128 = 6128.