Considere

\( f(x) \, = \, \begin {vmatrix} x \, log(2i) \,\, -2 \\ x \, log(i) \,\,\,\,\,\,\,\,\,\,\,\, 2 \end {vmatrix}, \, com \,\, f \, : \, N \, \rightarrow \, C. \)

Mediante a isso, e considerando que log(i) = 0,68i, podemos afirmar que

\( \sum_{x=1}^4 \, f(x) \)