So I’m prepping for the SAT Math2c test using Barron’s, but the newest edition mentions relations; however, nothing about relations is on the practice test for CollegeBoard. Should I study it anyway?
Why not? A little bit more effort means you’re prepared if they do show up. A single practice test may not contain all of the possible topics (as you’ll learn in college when occasionally the real test is nothing at all like the practice one).