$\newcommand{\+}{^{\dagger}} \newcommand{\angles}[1]{\left\langle\, #1 \,\right\rangle} \newcommand{\braces}[1]{\left\lbrace\, #1 \,\right\rbrace} \newcommand{\bracks}[1]{\left\lbrack\, #1 \,\right\rbrack} \newcommand{\ceil}[1]{\,\left\lceil\, #1 \,\right\rceil\,} \newcommand{\dd}{{\rm d}} \newcommand{\down}{\downarrow} \newcommand{\ds}[1]{\displaystyle{#1}} \newcommand{\expo}[1]{\,{\rm e}^{#1}\,} \newcommand{\fermi}{\,{\rm f}} \newcommand{\floor}[1]{\,\left\lfloor #1 \right\rfloor\,} \newcommand{\half}{{1 \over 2}} \newcommand{\ic}{{\rm i}} \newcommand{\iff}{\Longleftrightarrow} \newcommand{\imp}{\Longrightarrow} \newcommand{\isdiv}{\,\left.\right\vert\,} \newcommand{\ket}[1]{\left\vert #1\right\rangle} \newcommand{\ol}[1]{\overline{#1}} \newcommand{\pars}[1]{\left(\, #1 \,\right)} \newcommand{\partiald}[3][]{\frac{\partial^{#1} #2}{\partial #3^{#1}}} \newcommand{\pp}{{\cal P}} \newcommand{\root}[2][]{\,\sqrt[#1]{\vphantom{\large A}\,#2\,}\,} \newcommand{\sech}{\,{\rm sech}} \newcommand{\sgn}{\,{\rm sgn}} \newcommand{\totald}[3][]{\frac{{\rm d}^{#1} #2}{{\rm d} #3^{#1}}} \newcommand{\ul}[1]{\underline{#1}} \newcommand{\verts}[1]{\left\vert\, #1 \,\right\vert} \newcommand{\wt}[1]{\widetilde{#1}}$ $\ds{\int_{0}^{\infty}{\ln^{2}\pars{x} \over x^{2} + 4}\,\dd x:\ {\large ?}}$ .
\begin{align}&\color{#c00000}{\int_{0}^{\infty} {\ln^{2}\pars{x} \over x^{2} + 4}\,\dd x} =\int_{0}^{\infty}{\ln^{2}\pars{x^{1/2}} \over x + 4}\,\half\,x^{-1/2}\,\dd x ={1 \over 8}\int_{0}^{\infty}{x^{-1/2}\ln^{2}\pars{x} \over x + 4}\,\dd x \\[3mm]&={1 \over 8}\lim_{\mu \to -1/2}\partiald[2]{}{\mu} \color{#00f}{\int_{0}^{\infty}{x^{\mu} \over x + 4}\,\dd x}\tag{1} \end{align}
Con el siguiente contorno, la integral se evalúa fácilmente:
\begin{align}&\color{#00f}{\int_{0}^{\infty}{x^{\mu} \over x + 4}\,\dd x} =2\pi\ic\pars{4^{\mu}\expo{\ic\pi\mu}} -\int_{\infty}^{0}{x^{\mu}\expo{2\pi\ic\mu} \over x + 4}\,\dd x \end{align}
$$ \color{#00f}{\int_{0}^{\infty}{x^{\mu} \over x + 4}\,\dd x} =2\pi\ic\,{4^{\mu}\expo{\ic\pi\mu} \over 1 - \expo{2\pi\ic\mu}} =-\pi\,{4^{\mu} \over \sin\pars{\pi\mu}} $$
\begin{align}& \partiald[2]{}{\mu}\color{#00f}{\int_{0}^{\infty}{x^{\mu} \over x + 4}\,\dd x} \\[3mm]&=-2^{2m}\,\pi\,\csc\pars{\pi \mu}\braces{\vphantom{\LARGE A} \pi^2\bracks{\vphantom{\Large A}2\csc^{2}\pars{\pi\mu} - 1} -4\pi\ln\pars{2}\cot\pars{\pi\mu} + 4\ln^{2}\pars{2}} \end{align}
\begin{align}&\lim_{\mu \to -1/2} \partiald[2]{}{\mu}\color{#00f}{\int_{0}^{\infty}{x^{\mu} \over x + 4}\,\dd x} =\half\,\pi^{3} + 2\pi\ln^{2}\pars{2} \end{align}
Sustitución en $\pars{1}$ : $$\color{#66f}{\large\int_{0}^{\infty} {\ln^{2}\pars{x} \over x^{2} + 4}\,\dd x} = \color{#66f}{\large{1 \over 16}\,\pi^{3} + {1 \over 4}\,\pi\ln^{2}\pars{2}} \approx 2.3152 $$
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Puede utilizar este técnica .