You do not really need a computer program to solve this equation. In reality you have an equation of the type \begin{equation} \alpha + 2x + 2 \sqrt{\beta + \alpha x + x^2} = f(\alpha, \beta, a, t) =: f. \end{equation} You convert into something more manageable by noticing that this equation implies \begin{equation} \left( 2 \sqrt{\beta + \alpha x + x^2} \right)^2 = 4 \left( \beta + \alpha x + x^2 \right) = (f - \alpha - 2 x)^2 \end{equation} which you can easily convert to a second degree equation in $x$. Take care and insert your solution in the original equation.