Long ago, humankind didn’t accept fractions, only whole numbers could be counted. Then people could count only positive quantities, because negative numbers were impossible for them to imagine. After negative numbers became familiar, the square roots of negative real numbers were defined, producing imaginary numbers. The resulting quantities were combined with real numbers to get complex numbers. You were introduced to imaginary and complex numbers earlier in this book. Now, you’ll learn how to work with these numbers and find out how they can be useful in solving problems that would be much more difficult without them.
Think of all the real numbers as points on a straight line. A certain point is ...