-
A number that has both a real part and an imaginary part, written in the form a + ib, in which a and b are real numbers and i is the square root of -1 (that is, i2 = -1).
Complex numbers were introduced to solve the type of algebra equations such as x2 + 2 = 0, which does not have any solution without the help of complex numbers because real numbers do not include square roots of negative numbers.
Another way to look at complex numbers is that these types of numbers provide a means to treat two numbers, which are different, but closely related, as one entity.
