Sub test()
derForm = Cells(Rows.Count, 3).End(xlUp).Row 'dernière formule en colonne C
derLigUtil = Cells(Rows.Count, 2).End(xlUp).Row 'dernière cellule non-vide en colonne B
Range(Cells(derForm, 3), Cells(derLigUtil, 3)).Formula = Cells(derForm, 3).Formula
End Sub