If S_{1} and S_{2} are respectively the sets of local minimum and local maximum points of the function, f(x) = 9x^{4} + 12x^{3} − 36x^{2} + 25, x R, then

If S_{1} and S_{2} are respectively the sets of local minimum and local maximum points of the function, f(x) = 9x^{4} + 12x^{3} − 36x^{2} + 25, x R, then

Whenever derivative changes sign from negative to positive, we get local minima, and whenever derivative changes sign from positive to negative, we get local maxima (while moving left to right on x-axis)