Elon Musk is leaving Washington after a tenure in government marked by controversy.

He clashed with cabinet secretaries. He took a chain-saw approach to slashing government jobs. He never came close to cutting $1 trillion from the federal budget, like he had promised.

On Friday, President Trump gave him a send-off in the Oval Office that was meant to give him a boost as he turns his focus back to his businesses.

Mr. Musk, dressed in black and sporting a black eye, stood next to the president during a joint news conference. Here are six takeaways:

Trump is standing by Musk.

Mr. Trump wanted to send the message that he still supports his billionaire benefactor, who donated about $275 million to help him win the presidency.

The president presented Mr. Musk with a golden key and portrayed him as a victim of unfair scrutiny.

“He had to go through the slings and the arrows, which is a shame,” Mr. Trump said.

Tesla, Mr. Musk’s carmaker, has faced protests, vandalism and plummeting stock prices as the billionaire deepened his involvement with right-wing politics.

The relationship between the two men started out rocky. Mr. Musk once suggested Mr. Trump shouldn’t run for office, and the president brushed him off.