(b)
Let$\ u = \log_{10}{x\ and\ \ v = x^{2}}$
$\therefore\frac{du}{dx} = \frac{\log_{10}e}{x}\ \ and\ \ \ \ \ \ \frac{\ \ dv}{dx} = 2x$
$\therefore\$ $\frac{du}{dv} = \frac{du\ /dx}{dv\ /dx} = \frac{\log_{10}e}{x}/2x\$
$= \frac{\log_{10}e}{2x^{2}}$