\[\boxed{\mathbf{52}\mathbf{.}}\]
\[\textbf{а)}\ f(x) = \pi^{x} + e^{x};\ \ x \in R\]
\[f^{'}(x) = \left( \pi^{x} \right)^{'} + \left( e^{x} \right)^{'} =\]
\[= \pi^{x}\ln\pi + e^{x}.\]
\[\textbf{б)}\ f(x) = x^{e} - x^{\pi};\ \ x > 0\]
\[f^{'}(x) = \left( x^{e} \right)^{'} - \left( x^{\pi} \right)^{'} =\]
\[= ex^{e - 1} - \pi x^{\pi - 1}.\]
\[\textbf{в)}\ f(x) = \pi^{x} + x^{\pi};\ \ x > 0\]
\[f^{'}(x) = \left( \pi^{x} \right)^{'} + \left( x^{\pi} \right)^{'} =\]
\[= \pi^{x}\ln\pi + \pi x^{\pi - 1}.\]
\[\textbf{г)}\ f(x) = x^{e} - e^{x};\ \ x > 0\]
\[f^{'}(x) = \left( x^{e} \right)^{'} - \left( e^{x} \right)^{'} =\]
\[= ex^{e - 1} - e^{x}.\]