Y=-2x+bx is a quadratic function with downward opening, and the symmetry axis x=b/4. One * * * two boxes 1. The symmetry axis falls on the interval (0, 1) (pay attention to opening and closing the interval later). At this point, the vertex of the quadratic function is less than 1. The symmetry axis is not in the interval (0, 1), so the quadratic function is monotonous at (0, 1) as long as the values of the two ends of the interval are less than 1.