Reply To: boldface variable
Hullo, Susan!
I would say that it is safe to ignore the bold for all of the i's in your worksheet.
The heading of the worksheet, "Complex Numbers", does indicate that the i's represent imaginary numbers. Since there is no indication that the i's represent a vector or anything else that would have to be denoted by boldface, it appears that the bold is used in print only for appearance.
Thank you for the question.
–Kyle