Given f(x)=x3−6x2+9xf(x) = x^3 - 6x^2 + 9xf(x)=x3−6x2+9x, find all values of xxx where the tangent line is horizontal.
x=0,3x = 0, 3x=0,3
x=1,3x = 1, 3x=1,3
x=0,1x = 0, 1x=0,1
x=2,3x = 2, 3x=2,3