Imaginary unit

Rare card · No. 74953

The imaginary unit, usually denoted by i, is a mathematical constant that is a solution to the quadratic equation x2 = −1, which is not solved by any real number. Any real-number multiple of the imaginary unit is called an imaginary number. By combining the real numbers with the imaginary unit using addition and multiplication, a new number system known as the complex numbers is formed; it consists of all numbers of the form a + bi with real numbers a and b. The number −1 has two distinct complex square roots: i and its additive inverse −i. More generally, every nonzero complex number has two distinct complex-valued square roots, which are additive inverses of each other, while zero has only zero as its (double) square root. Historically, the imaginary unit was denoted by ⁠ − 1 {\displaystyle {\sqrt {-1}}} ⁠, though this is now rare. In contexts in which use of the letter i is ambiguous or...

Read on Wikipedia · Image Loadmaster (David R. Tribble) This image was made by Loadmaster (David R. Tribble). Email the author: David R. Tribble Also see my personal gallery at Google Photos, CC BY-SA 3.0