Given f'(x)=9/2x(3x^2+2)^1/2 (this is the derivative of y= sqrt[(3x^2+2)^3]) , state any values of x for which the function is not differentiable
well, for f(x) to be differentiable, f'(x) must be defined.
Surely you can see that 9x / 2√(3x^2+2) is defined for all real x...