CREATE TABLE table_764 ("District" CLOB, "Incumbent" CLOB, "Party" CLOB, "First elected" FLOAT, "Result" CLOB, "Candidates" CLOB)

When was the Tennessee 3 district incumbent first elected?
SELECT MAX("First elected") FROM table_764 WHERE "District" = 'Tennessee 3'
SELECT MAX("First elected") FROM "table_764" WHERE "District" = 'Tennessee 3'