The following is copy/paste from the online textbook. I thought this reading was pretty funny. The (square root) sign doesn't copy and paste, so I had to fill that in. Apparently blogger (Word does the same) thinks THAT is imaginary!


The form a + bi is called the standard form of a complex number. The real number a is called the real part of the complex number, and b is called the imaginary part. (Note that b is a real number even though it is called the imaginary part.) The following list exemplifies this terminology.

* 1. The number 7 + 5i is a complex number that has a real part of 7 and an imaginary part of 5.
* 2. The number 2/3 + i(Square root)2 is a complex number that has a real part of and an imaginary part of . (It is easy to mistake (square root) 2i for (square root) 2i . Thus it is customary to write i(square root) 2 instead of (square root) 2i to avoid any difficulties with the radical sign.)
* 3. The number −4 − 3i can be written in the standard form −4 + (−3i) and therefore is a complex number that has a real part of −4 and an imaginary part of −3. (The form −4 − 3i is often used, but we know that it means −4 + (−3i).)
* 4. The number −9i can be written as 0 + (−9i); thus it is a complex number that has a real part of 0 and an imaginary part of −9. (Complex numbers, such as −9i, for which a = 0 and b fi 0 are called pure imaginary numbers.)
* 5. The real number 4 can be written as 4 + 0i and is thus a complex number that has a real part of 4 and an imaginary part of 0.