What are imaginary numbers?

Imaginary numbers are any numbers that include the imaginary number i. A mix of imaginary and real numbers gives you what’s called a complex number.

The primary reason we use imaginary numbers is to give us a way to find the root (radical) of a negative number. There’s no way to use real numbers to find the root of a negative number, which prevents us from solving even simple polynomial equations.

But with imaginary numbers, we define the square root of -1 as the imaginary number i, and that allows us to easily find the roots of imaginary numbers.

0:21 // Are imaginary numbers real numbers?
0:45 // Examples of real and imaginary numbers
1:22 // The definition of the imaginary number i
1:39 // Why do we need imaginary numbers?
1:53 // Why is the imaginary number helpful?
2:52 // What happens when you square the imaginary number?

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