Question: What is the start date with Luke Jacobz hosting and Dannii Minogue as a winning mentor?
SQL: SELECT "Start" FROM "2-1658647-1" WHERE "Main host" = 'Luke Jacobz' AND "Winning mentor" = 'Dannii Minogue';

Question: Who was in third place when Guy Sebastian was the winning mentor and Andrew Wishart was the runner-up?
SQL: SELECT "Third place" FROM "2-1658647-1" WHERE "Winning mentor" = 'Guy Sebastian' AND "Runner-up" = 'Andrew Wishart';