It is known that the image of inverse scale function y = K / X passes through (1 / 2,8), and the line y = - x + B should pass through the image of inverse scale function (4, m) to find their inverse scale function and the function expression of the line
Because the image of y = K / X passes through (1 / 2,8), then: 8 = 2K, k = 4, that is: y = 4 / X
Because the line y = - x + B should pass through the image of inverse scale function (4, m), then point (4, m) is on the line and inverse scale function: M = 4 / 4 = 1, substituting y = - x + B to get: 1 = - 4 + B, B = - 5. That is y = - X-5