[(x-1)(x-4)][(x+3)(x-8)]+m=[(x-5/2)^2-9/4][(x-5/2)^2-121/4]+m=(x-5/2)^4-65/2*(x-5/2)^2+1089/16+m
所以1089/16+m=(65/4)^2
所以m=196