Quickly get first and last day of month

public static class DateTimeExtension
{
    public static DateTime FirstDayOfMonth(this DateTime bsaeDate)
    {
        //return new DateTime(bsaeDate.Year, bsaeDate.Month, 1);
        return bsaeDate.AddDays(-bsaeDate.Day + 1);
    }

    public static DateTime LastDayOfMonth(this DateTime baseDate)
    {
        //return new DateTime(baseDate.Year, baseDate.Month + 1, 1).AddDays(-1);
        return baseDate.AddMonths(1).AddDays(-baseDate.AddMonths(1).Day);
    }
}