İntegralimiz :
$$\Xi(1,1)=\int_0^1\:\frac{\ln(x)}{1+x}\:dx$$
Buradaki eşitlikte $n$ yerine $1$ verelim.Eşitlik :
$$\Xi(n,1)=\int_0^1\:\frac{\ln^n(x)}{1+x}\:dx=(-1)^n\:(1-2^{-n})\:\Gamma(n+1)\zeta(n+1)$$
$$\Xi(1,1)=\int_0^1\:\frac{\ln(x)}{1+x}\:dx=-2^{-1}\:\Gamma(2)\zeta(2)$$
$$\large\color{#A00000}{\boxed{\Xi(1,1)=\int_0^1\:\frac{\ln(x)}{1+x}\:dx=-\frac{\pi^2}{12}}}$$