Today’s SAT question of the day is a medium-difficulty math question that asks us about the term “undefined”.  Undefined, for the purposes of the SAT, means that we’d be dividing by zero. Every time you see that word, translate it into “divide by zero.”

Today we need to know what value of x would make this equation undefined for y:

In other words, we need to make the denominator 0.

If x was -3, since -3 + 3 = 0 and anything times 0 is 0, that would work.

If x was 4, since 4 – 4 = 0 and anything times 0 is 0, that would work.

Of those two options, only -3 appears in our answer choices. Done!

Note that even though we need to be fluent in algebra in order to complete this question, we didn’t actually have to do any math!  This is just a reasoning question – a question that requires us to think but doesn’t require any significant calculations.  They can be quick and easy if you stay focused on what the question is asking and remember terms (like “undefined”).