Pull It Away!

Work done $dW = qEdl$

$dW = q \dfrac {\sigma}{2\epsilon_0} dl$

${\color{#20A900}{\sigma = \dfrac {Q}{4πr^2}}}$

$W = \displaystyle \int _0^W dW = \displaystyle \int _l^\infty q\times \dfrac {q}{2\times 4π\epsilon_0 (\sqrt{2}l)^2} dl = \dfrac {q^2}{2\times 4π\epsilon_0 \times 2} \begin{vmatrix} -\dfrac 1l \end{vmatrix}_l^\infty = \dfrac {q^2}{16π\epsilon_0}\begin{pmatrix} \dfrac 1l - \dfrac 1\infty \end{pmatrix} = \dfrac {1}{16} \dfrac {q^2}{π\epsilon_0l}$

Therefore, $a + b = 1 + 16 = \boxed{17}$

Is my solution even appropriate? Please let me know