Si $f$, $g$, y $h$ son funciones derivables de $x$ y se define:
$$\Delta(x) = \begin{vmatrix} f & g & h \\ (xf)' & (xg)' & (xh)' \\ (x^2 f)' & (x^2 g)' & (x^2 h)' \end{vmatrix}$$
entonces demuestre que:
$$\Delta'(x) = \begin{vmatrix} f & g & h \\ f' & g' & h' \\ (x^3 f'')' & (x^3 g'')' & (x^3 h'')' \end{vmatrix}$$