In the plane rectangular coordinate system, after translating the line y = - 2x + 1 down four unit lengths, the analytical expression of the line is______ .

In the plane rectangular coordinate system, after translating the line y = - 2x + 1 down four unit lengths, the analytical expression of the line is______ .

From the meaning of the question: the translation of the analytical formula is: y = - 2x + 1-4 = y = - 2x-3