1.57=x/((1.28-x)^2) rearrange by multiplying both sides by the denominator on the right side
1.57(1.28 - x)^2 = x expand
1.57(1.6384 - 2.56x + x^2) = x simplify
2.572288 - 4.0192x + 1.57x^2 = x subtract x from both sides
1.57x^2 - 5.0192x + 2.572288 = 0
This is probably best solved by using the onsite solver
$${\mathtt{1.57}}{\mathtt{\,\times\,}}{{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{5.019\: \!2}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{2.572\: \!288}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{\,-\,}}{\frac{\left({\mathtt{50}}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{5\,649}}}}{\mathtt{\,-\,}}{\mathtt{6\,274}}\right)}{{\mathtt{3\,925}}}}\\
{\mathtt{x}} = {\frac{\left({\mathtt{50}}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{5\,649}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{6\,274}}\right)}{{\mathtt{3\,925}}}}\\
\end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{0.641\: \!021\: \!277\: \!752\: \!175\: \!7}}\\
{\mathtt{x}} = {\mathtt{2.555\: \!921\: \!397\: \!407\: \!06}}\\
\end{array} \right\}$$
