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。

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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.

当夏洛特·霍布斯决定教她11岁的学生用来计算负数平方根的虚数时，她知道这是一个艰巨的任务。

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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

耶鲁公开课 - 金融市场课程节选

An imaginary one is a multiple of the square root of -1.

ECONOMIST: Beno?t Mandelbrot