Concavity and Inflection Points

Let f′′(x)=6x2(x−1)(x2−6)3/2(x−3)3f''(x)=\frac{6x^2\left(x-1\right)}{(x^2-6)^{3/2}(x-3)^3}

Final all intervals where f(x)f(x) is concave down.
More Concavity and Inflection Points Questions: