The traditional way an math objective question is posed using the exerquiz command \RespBoxMath is to leave a blank text field into which the student enters his or her response to the question. An alternate strategy is to supply an incorrect answer (that looks correct) and to ask the student to edit the answer to obtain a correct answer.
To learn more about this type of question, download correct-type.pdf to your own computer and open it in Adobe Acrobat Reader (or in the Acrobat application if you have it). Browser support has regressed.
exerquiz dated 2017/09/03 or later required.