If you had one negative number in it, then the product would be a negative number and, if you took a root of that, then you might get an imaginary number.
如果这当中有一个负数，乘积就会变成负的，如果你对一个负数开根号，你就会得到一个虚数。
2
In fact, it can generally be a complex number with both a "real" part that's an ordinary number and an "imaginary" part that's multiplied by the square root of one.
事实上，它通常是一个复数的形式，包括普通数字的实数部分和需要乘以负一的平方根的虚部。
3
WHEN Charlotte Hobbs decided to teach her 11-year-old pupil about the "imaginary" maths needed to work out the square root of a negative number, she knew it would be a stretch.