The set of points where f(x)=(x-1)2(x+|x-1|) is thrice differentiable, is
R
R-{0}
R-{1}
R-{0,1}
Since |x| is not diff. at x=0⇒|x−1| is not diff at x=1 . xn|x| is n times diff. at x=0∴x-12|x−1| is twice diff. at x=1 but not thrice diff. at x=1