f(x)=|(x-1)(x-2)^2.(x-3)^3| =(x-2)^2.(x-3)^2 |(x-1)(x-3)|ief(x) =-(x-2)^2.(x-3)^2.(x-1)(x-3) ; 1≤x≤3 =(x-2)^2.(x-3)^2.(x-1)(x-3) ; elsewheref'(x) 不存在点个数 = 2Ans: C
