Newcastle edged a first half in which Arsenal failed to get going, but the Gunners were a completely different team after the break, as Mesut Ozil started to find more space to cause the visitors problems, and youngster Bukayo Saka superb throughout.
Pierre-Emerick Aubameyang opened the scoring with a fine header, Nicolas Pepe turned in a Saka cutback before Ozil and Lacazette ended their respective goal droughts to finish off a fine second-half display.
Arteta told BBC Sport: “After the break we started saying we had to start closing the gap on the top teams and turn draws into wins. Today was the first opportunity and we’ve done it. All good.
“I’m so pleased for Laca [Alexandra Lacazette] – the reaction of the players and staff towards him. He fights hard for everyone. He’s been unlucky. He will gain confidence from this and knows how everyone appreciates him.
“Bukayo Saka is doing really well. He keeps his head down and wants to learn. He’s peforming like a senior player.
“Dani Ceballos is a good example. He was injured and when he started to train I didn’t think he was fit enough. He completely changed his behaviour and trained like an animal. I thought he was the best player on the pitch.”
On competing for a European place and Manchester City Arteta added: “Ten days ago I was disappointed with the draw at Burnley and it looked so far away. Now it’s up to us to put a run together.
“Very difficult. [I am] Not conflicted at all. I want the best for Manchester City, for Pep, for the players. The only thing I want for them was positive and good things. I want us to do the best we can to achieve what we can deserve.”