Square rootIn mathematics, a square root of a number x is a number y such that ; in other words, a number y whose square (the result of multiplying the number by itself, or ) is x. For example, 4 and −4 are square roots of 16 because . Every nonnegative real number x has a unique nonnegative square root, called the principal square root, which is denoted by where the symbol "" is called the radical sign or radix. For example, to express the fact that the principal square root of 9 is 3, we write .
Axis powersThe Axis powers, originally called the Rome–Berlin Axis, was a military coalition that initiated World War II and fought against the Allies. Its principal members were Nazi Germany, the Kingdom of Italy, and the Empire of Japan. Alongside Italy, Romania and Hungary may also be considered among "the Reich's main allies". The Axis were united in their far-right positions and general opposition to the Allies, but otherwise lacked comparable coordination and ideological cohesion.
Central PowersThe Central Powers, also known as the Central Empires, were one of the two main coalitions that fought in World War I (1914–1918). It consisted of Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria; this was also known as the Quadruple Alliance. The Central Powers' origin was the alliance of Germany and Austria-Hungary in 1879. Despite having nominally joined the Triple Alliance before, Italy did not take part in World War I on the side of the Central Powers. The Ottoman Empire and Bulgaria did not join until after World War I had begun.
AlgebraAlgebra () is the study of variables and the rules for manipulating these variables in formulas; it is a unifying thread of almost all of mathematics. Elementary algebra deals with the manipulation of variables (commonly represented by Roman letters) as if they were numbers and is therefore essential in all applications of mathematics. Abstract algebra is the name given, mostly in education, to the study of algebraic structures such as groups, rings, and fields.
TetrationIn mathematics, tetration (or hyper-4) is an operation based on iterated, or repeated, exponentiation. There is no standard notation for tetration, though and the left-exponent xb are common. Under the definition as repeated exponentiation, means , where n copies of a are iterated via exponentiation, right-to-left, i.e. the application of exponentiation times. n is called the "height" of the function, while a is called the "base," analogous to exponentiation. It would be read as "the nth tetration of a".
