# complex number

## noun

1. a mathematical expression ( a + bi ) in which a and b are real numbers and i 2 = −1.

complex number

## noun

1. any number of the form a + i b , where a and b are real numbers and i = √–1 See number

complex number

/ kŏmplĕks′ /

1. A number that can be expressed in terms of i (the square root of −1). Mathematically, such a number can be written a + bi, where a and b are real numbers. An example is 4 + 5 i.

## Word History and Origins

Origin of complex number1

First recorded in 1825–35

## Example Sentences

John’s key insight was to use complex numbers, which can be added like vectors.

If we represent the second link as the complex number z, then the third link was z2, the fourth link was z3, and so on.

At this point, many readers caught on to the clue from the beginning — “hopefully not too complex” was in fact suggesting that you explore complex numbers.

Go ahead — pick a value for k and raise that complex number to the seventh power.

Provided that quantum mechanics is correct—an assumption few would quibble with—the team’s argument essentially guarantees that complex numbers are an unavoidable part of our description of the physical universe.