First of all: Please mark your code with code tags, otherwise the online editor/compiler will not work and moreover the formatting of the message may break the code.
You are already loading package amsmath, so why don't you use a multi-line environment like split? See section 3.3 and 3.4 of the user manual amsldoc for more information.
BTW: Since LaTeX 2018-04-01 \usepackage[utf8]{inputenc} is not needed anymore.
Sorry, but I can no longer participate here as the administrator is trampling on my wishes on one of his other platforms.
Use \begin{eqnarray}
to break equation is use \\ \nonumber {this can be done any number of times and at each level write \\\nonumber
\end{eqnarray}
I am sure that this will work. I am unable to compile it as there are many erroes and I do not know your equation form.
Although the standard eqnarray environment remains available, it is better to
use align or equation+split instead. Within eqnarray, spacing around signs
of relation is not the preferred mathematical spacing, and is inconsistent with
that spacing as it appears in other environments. Long lines in this environment
may result in misplaced or overprinted equation numbers. This environment also
does not support the use of \qed or \qedhere as provided by theorem packages.
So if you load amsmath it is not recommended to use eqnarray but one of the amsmath environments (as already suggested above). See the manual for more information.
Sorry, but I can no longer participate here as the administrator is trampling on my wishes on one of his other platforms.