Holders City remain on course to repeat their treble triumph of Premier League, Champions League and FA Cup last season as Pep Guardiola's men stretched their unbeaten run in all competitions to 22 games.
Fortune favoured the English champions, though, as twice Silva's shots took deflections to wrong-foot Newcastle goalkeeper Martin Dubravka. The Portuguese international opened the scoring on 13 minutes when his effort looped in off Dan Burn.
Silva's second deflected off Sven Botman, but Dubravka should still have done better as the ball trickled underneath him. At the other end, City's number one goalkeeper Ederson was not missed as Stefan Ortega produced a brilliant save to deny Alexander Isak pulling a goal back for Newcastle.