<p>on a math question (from the blue book), there was a question that looked like:</p>
<p>"For all positive integers x, let x(triangle sign) be defined to be (x-1)(x+1). Which of the following is equal to 6(triangle sign) - 5(triangle sign)"</p>
<p>What is that triangle sign?</p>
<p>And can anyone provide a list of SAT math symbols that aren't commonly used?</p>