Finding start date and end date for half year

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SQL-Server-2012

Msg 102, Level 15, State 1, Line 2
Incorrect syntax near '_'.
Msg 102, Level 15, State 1, Line 8
Incorrect syntax near '-1-'.

What I have tried:

select @beginDate =
CAST(CAST(((((MONTH(GETDATE()) - 1) / 6) * 6) + 1) _
AS VARCHAR) + '-1-' + CAST(YEAR(GETDATE()) AS VARCHAR) AS DATETIME);

select @endDate =
CAST(CAST(((((MONTH(GETDATE()) - 1) / 6) * 6) + 6) AS VARCHAR) + _

'-1-' + CAST(YEAR(GETDATE()) AS VARCHAR) AS DATETIME);