A complex number can be visually represented as a pair of numbers (a, b) forming a vector on a diagram called an Argand diagram, representing the complex plane. Re is the real axis, Im is the imaginary axis, and i is the imaginary unit which satisfies i2 = â1.
When discussing blood types, the two groupings most commonly used are the ABO (A, B, AB, O) and Rh (+, -) systems. The least common blood type in humans is Bombay (EXTREMELY râ¦are), which is a type O with missing H antigen. Otherwise, of the normal ABO and Rh typings, the least common group is AB-.
Blood group: An inherited feature on the surface of the red blood cells. A series of related blood types constitutes a blood group system, such as the Rh or ABO system. The frequencies of the ABO and Rh blood types vary from population to population.In the US, the most common type is O+ (meaning O in the ABO system and positive in the Rh system), which is present in 37.4 percent of the population.he frequencies of the ABO and Rh blood types vary from population to population. In the US, the most common type is O+ (meaning O in the ABO system and positive in the Rh system), which is present in 37.4 percent of the population.