ELI5: Explain Like I'm 5

Trivial (mathematics)

In math, "trivial" means something is really easy and obvious. It's like asking what's 1+1? The answer is 2, and everyone knows it without having to think very hard. That's a "trivial" math problem. So, when a math problem or solution is called "trivial," it means it's not difficult to figure out and doesn't require much thinking to solve.