x4-8x3+22x2-24x+25 . how can we define it increasing & decreasing area if its answer is (x-1) (x-2) x-3). I-powers

as its factor are 1 , 2 and 3 . draw all these on number line and give alternative + and - sign starting from right to left . the portion where there is a positive sign is increasing area and where there is a - sign is decresing area . and acc to this questin the incresing area is (1,2)υ (3,∞) and the remaining area is decreasing