X and Y
These are two magical words we can find everywhere These words are often used in science to represent any entities, especially in mathematical formulations. I was wondering why differential equation often represent as dy/dx not da/db ? Why Male Chromosome is represented by xy rather than ab ? Why Female Chromosome is represented by xx rather than aa ? Why random variables in probabilities and statistics theories generally represented by X , not R ? Why function f( x ) is defined as the rule that map x to y ? Why don't we define function f( p ) as the rule that map p to q instead ? Why two dimensional vector generally use x and y to represent the dimensions ? Why don't we use a and b instead ? Why the equation of linear regression is formulated as y =a x +b and not q =a p +b? In daily life, x is used to represent some mysterious or unknown entities for example: Where the cashflow from Mr. X goes to? see? Yet, it's used for some negative interp...