x1 = 2/3 y1 = -3/2x2 = -1/2 y2 = 2x3 = 3 y3 = -1/3x4 = 2/3 y4 = -3/2所以可以看出规律yn每隔3个循环一次也就是周期是3所以 y4 = -3/2 y5 = y2 = 2因为2009/3 = 699 余2所以 y2009 = y2 = 2...