<p>To me, “I studied math” seems more relevant to a single occasion.
(i.e. “Yesterday, I studied math with Bob.”)
“I have studied math” would likely indicate multiple occasions, and would be appropriate when describing an action over a course of time.
(i.e. “I have studied math for the past four years.”)</p>
<p>However, the difference is so slight that I highly doubt utilizing it either way would be looked down upon. If you have to air on the side of one or the other, I would cut the “have” and just use “I studied math” for conciseness. </p>
<p>Just my opinion! :)</p>