I've been grading calculus exams this week, and even though my students did quite well overall there were a couple of errors that I see every semester. Errors that make mathematicians' heads explode.

This equation is in the standard form of a linear equation: A x + B y = C, where A, B, and C are constants. The variable x is raised to the power of 1. The variable y is raised to the power of 1. The ...