Use formulas to generate multiple-choice answers: one correct formula for the correct choice and use incorrect formulas to generate incorrect choices.
For math, physics, and related courses, the formula question option, though limited, seems to be the best tool available to generate unique, randomized, student-specific tests that can be tracked online posting (we still desperately need the option to have multiple formula answers fields in a single question). However, a simple mistake in a formula question can cost the entire points because students will have no idea what the possible answer would be. Therefore, it seems unfair to ask such a question if the instructor is not giving partial credit. One way to avoid this would be to allow multiple choices but then the problem does not become a formula question. It would really help if we can not only generate the correct answer, but also choices of incorrect answers.
One of the most frustrating issues in online exams is cheating and the technology to assist cheating seems to be moving faster than to prevent it. Therefore, it is a very pressing issue.