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c# - How to I use TryParse in a linq query of xml data?

I'm working with in memory xml of daily stock market data, and I'm getting the value "8/221/19055" for one of the dates. I see that TryParse is likely my best bet to check for a valid date, but the MSDN doc seems light on an explanation of the 2nd parameter "out DateTime result." How can I use it in my linq query below?

var makeInfo =
         from s in doc.Descendants("quote")
         where s.Element("LastTradeDate") != null
                && s.Attribute("symbol") != null
         let dateStr = s.Element("LastTradeDate").Value
         where !string.IsNullOrEmpty(dateStr)
                && DateTime.Parse(dateStr, enUS) == targetDate
         select new DailyPricingVolDP((string)s.Attribute("symbol"),
                                      (DateTime)s.Element("LastTradeDate"),
                                      (double)s.Element("Open"),
                                      (double)s.Element("DaysHigh"),
                                      (double)s.Element("DaysLow"),  
                                      (double)s.Element("LastTradePriceOnly"),
                                       (long)s.Element("Volume"));
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Func<string, DateTime?> tryToGetDate =
        value =>
            {
                DateTime dateValue;
                return DateTime.TryParse(value, out dateValue) ? (DateTime?) dateValue : null;
            };

    var makeInfo =
         from s in doc.Descendants("quote")
         where s.Element("LastTradeDate") != null
                && s.Attribute("symbol") != null
         let dateStr = s.Element("LastTradeDate").Value
         let dateValue = tryToGetDate(dateStr)
         where dateValue != null && (DateTime)dateValue == targetDate
         select .... etc etc

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